Remove support for empty queries (#22092)

Our query DSL supports empty queries (`{}`), which have a different meaning depending on the query that holds it, either ignored, match_all or match_none. We deprecated the support for empty queries in 5.0, where we log a deprecation warning wherever they are used.

The way we supported it once we moved query parsing to the coordinating node was having an Optional<QueryBuilder> return type in all of our parse methods (called fromXContent). See #17624. The central place for this was QueryParseContext#parseInnerQueryBuilder. We can now remove all the optional return types and simply throw an exception whenever an empty query is found.

core/src/main/java/org/elasticsearch/cluster/metadata/AliasValidator.java

@@ -33,7 +33,6 @@ import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.indices.InvalidAliasNameException;
 
 import java.io.IOException;
-import java.util.Optional;
 import java.util.function.Function;
 
 /**
@@ -139,10 +138,8 @@ public class AliasValidator extends AbstractComponent {
 
     private static void validateAliasFilter(XContentParser parser, QueryShardContext queryShardContext) throws IOException {
         QueryParseContext queryParseContext = queryShardContext.newParseContext(parser);
-        Optional<QueryBuilder> parseInnerQueryBuilder = queryParseContext.parseInnerQueryBuilder();
+        QueryBuilder parseInnerQueryBuilder = queryParseContext.parseInnerQueryBuilder();
-        if (parseInnerQueryBuilder.isPresent()) {
+        QueryBuilder queryBuilder = QueryBuilder.rewriteQuery(parseInnerQueryBuilder, queryShardContext);
-            QueryBuilder queryBuilder = QueryBuilder.rewriteQuery(parseInnerQueryBuilder.get(), queryShardContext);
         queryBuilder.toFilter(queryShardContext);
     }
-    }
 }

core/src/main/java/org/elasticsearch/index/query/BoolQueryBuilder.java

@@ -37,7 +37,6 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.function.Consumer;
 
 import static org.elasticsearch.common.lucene.search.Queries.fixNegativeQueryIfNeeded;
@@ -299,7 +298,7 @@ public class BoolQueryBuilder extends AbstractQueryBuilder<BoolQueryBuilder> {
         builder.endArray();
     }
 
-    public static Optional<BoolQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException, ParsingException {
+    public static BoolQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException, ParsingException {
         XContentParser parser = parseContext.parser();
 
         boolean disableCoord = BoolQueryBuilder.DISABLE_COORD_DEFAULT;
@@ -323,17 +322,17 @@ public class BoolQueryBuilder extends AbstractQueryBuilder<BoolQueryBuilder> {
             } else if (token == XContentParser.Token.START_OBJECT) {
                 switch (currentFieldName) {
                 case MUST:
-                    parseContext.parseInnerQueryBuilder().ifPresent(mustClauses::add);
+                    mustClauses.add(parseContext.parseInnerQueryBuilder());
                     break;
                 case SHOULD:
-                    parseContext.parseInnerQueryBuilder().ifPresent(shouldClauses::add);
+                    shouldClauses.add(parseContext.parseInnerQueryBuilder());
                     break;
                 case FILTER:
-                    parseContext.parseInnerQueryBuilder().ifPresent(filterClauses::add);
+                    filterClauses.add(parseContext.parseInnerQueryBuilder());
                     break;
                 case MUST_NOT:
                 case MUSTNOT:
-                    parseContext.parseInnerQueryBuilder().ifPresent(mustNotClauses::add);
+                    mustNotClauses.add(parseContext.parseInnerQueryBuilder());
                     break;
                 default:
                     throw new ParsingException(parser.getTokenLocation(), "[bool] query does not support [" + currentFieldName + "]");
@@ -342,17 +341,17 @@ public class BoolQueryBuilder extends AbstractQueryBuilder<BoolQueryBuilder> {
                 while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
                     switch (currentFieldName) {
                     case MUST:
-                        parseContext.parseInnerQueryBuilder().ifPresent(mustClauses::add);
+                        mustClauses.add(parseContext.parseInnerQueryBuilder());
                         break;
                     case SHOULD:
-                        parseContext.parseInnerQueryBuilder().ifPresent(shouldClauses::add);
+                        shouldClauses.add(parseContext.parseInnerQueryBuilder());
                         break;
                     case FILTER:
-                        parseContext.parseInnerQueryBuilder().ifPresent(filterClauses::add);
+                        filterClauses.add(parseContext.parseInnerQueryBuilder());
                         break;
                     case MUST_NOT:
                     case MUSTNOT:
-                        parseContext.parseInnerQueryBuilder().ifPresent(mustNotClauses::add);
+                        mustNotClauses.add(parseContext.parseInnerQueryBuilder());
                         break;
                     default:
                         throw new ParsingException(parser.getTokenLocation(), "bool query does not support [" + currentFieldName + "]");
@@ -394,7 +393,7 @@ public class BoolQueryBuilder extends AbstractQueryBuilder<BoolQueryBuilder> {
         boolQuery.adjustPureNegative(adjustPureNegative);
         boolQuery.minimumNumberShouldMatch(minimumShouldMatch);
         boolQuery.queryName(queryName);
-        return Optional.of(boolQuery);
+        return boolQuery;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/BoostingQueryBuilder.java

@@ -31,7 +31,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 import java.io.IOException;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * The BoostingQuery class can be used to effectively demote results that match a given query.
@@ -137,12 +136,12 @@ public class BoostingQueryBuilder extends AbstractQueryBuilder<BoostingQueryBuil
         builder.endObject();
     }
 
-    public static Optional<BoostingQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static BoostingQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
-        Optional<QueryBuilder> positiveQuery = null;
+        QueryBuilder positiveQuery = null;
         boolean positiveQueryFound = false;
-        Optional<QueryBuilder> negativeQuery = null;
+        QueryBuilder negativeQuery = null;
         boolean negativeQueryFound = false;
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
         float negativeBoost = -1;
@@ -186,15 +185,12 @@ public class BoostingQueryBuilder extends AbstractQueryBuilder<BoostingQueryBuil
             throw new ParsingException(parser.getTokenLocation(),
                     "[boosting] query requires 'negative_boost' to be set to be a positive value'");
         }
-        if (positiveQuery.isPresent() == false || negativeQuery.isPresent() == false) {
-            return Optional.empty();
-        }
 
-        BoostingQueryBuilder boostingQuery = new BoostingQueryBuilder(positiveQuery.get(), negativeQuery.get());
+        BoostingQueryBuilder boostingQuery = new BoostingQueryBuilder(positiveQuery, negativeQuery);
         boostingQuery.negativeBoost(negativeBoost);
         boostingQuery.boost(boost);
         boostingQuery.queryName(queryName);
-        return Optional.of(boostingQuery);
+        return boostingQuery;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/CommonTermsQueryBuilder.java

@@ -40,7 +40,6 @@ import org.elasticsearch.index.mapper.MappedFieldType;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * CommonTermsQuery query is a query that executes high-frequency terms in a
@@ -263,7 +262,7 @@ public class CommonTermsQueryBuilder extends AbstractQueryBuilder<CommonTermsQue
         builder.endObject();
     }
 
-    public static Optional<CommonTermsQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static CommonTermsQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String fieldName = null;
@@ -348,7 +347,7 @@ public class CommonTermsQueryBuilder extends AbstractQueryBuilder<CommonTermsQue
             }
         }
 
-        return Optional.of(new CommonTermsQueryBuilder(fieldName, text)
+        return new CommonTermsQueryBuilder(fieldName, text)
                 .lowFreqMinimumShouldMatch(lowFreqMinimumShouldMatch)
                 .highFreqMinimumShouldMatch(highFreqMinimumShouldMatch)
                 .analyzer(analyzer)
@@ -357,7 +356,7 @@ public class CommonTermsQueryBuilder extends AbstractQueryBuilder<CommonTermsQue
                 .disableCoord(disableCoord)
                 .cutoffFrequency(cutoffFrequency)
                 .boost(boost)
-                .queryName(queryName));
+                .queryName(queryName);
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/ConstantScoreQueryBuilder.java

@@ -31,7 +31,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 import java.io.IOException;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * A query that wraps a filter and simply returns a constant score equal to the
@@ -86,10 +85,10 @@ public class ConstantScoreQueryBuilder extends AbstractQueryBuilder<ConstantScor
         builder.endObject();
     }
 
-    public static Optional<ConstantScoreQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static ConstantScoreQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
-        Optional<QueryBuilder> query = null;
+        QueryBuilder query = null;
         boolean queryFound = false;
         String queryName = null;
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
@@ -130,15 +129,10 @@ public class ConstantScoreQueryBuilder extends AbstractQueryBuilder<ConstantScor
             throw new ParsingException(parser.getTokenLocation(), "[constant_score] requires a 'filter' element");
         }
 
-        if (query.isPresent() == false) {
+        ConstantScoreQueryBuilder constantScoreBuilder = new ConstantScoreQueryBuilder(query);
-            // if inner query is empty, bubble this up to caller so they can decide how to deal with it
-            return Optional.empty();
-        }
-
-        ConstantScoreQueryBuilder constantScoreBuilder = new ConstantScoreQueryBuilder(query.get());
         constantScoreBuilder.boost(boost);
         constantScoreBuilder.queryName(queryName);
-        return Optional.of(constantScoreBuilder);
+        return constantScoreBuilder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/DisMaxQueryBuilder.java

@@ -34,7 +34,6 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * A query that generates the union of documents produced by its sub-queries, and that scores each document
@@ -122,7 +121,7 @@ public class DisMaxQueryBuilder extends AbstractQueryBuilder<DisMaxQueryBuilder>
         builder.endObject();
     }
 
-    public static Optional<DisMaxQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static DisMaxQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
@@ -140,7 +139,7 @@ public class DisMaxQueryBuilder extends AbstractQueryBuilder<DisMaxQueryBuilder>
             } else if (token == XContentParser.Token.START_OBJECT) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, QUERIES_FIELD)) {
                     queriesFound = true;
-                    parseContext.parseInnerQueryBuilder().ifPresent(queries::add);
+                    queries.add(parseContext.parseInnerQueryBuilder());
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), "[dis_max] query does not support [" + currentFieldName + "]");
                 }
@@ -148,7 +147,7 @@ public class DisMaxQueryBuilder extends AbstractQueryBuilder<DisMaxQueryBuilder>
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, QUERIES_FIELD)) {
                     queriesFound = true;
                     while (token != XContentParser.Token.END_ARRAY) {
-                        parseContext.parseInnerQueryBuilder().ifPresent(queries::add);
+                        queries.add(parseContext.parseInnerQueryBuilder());
                         token = parser.nextToken();
                     }
                 } else {
@@ -178,7 +177,7 @@ public class DisMaxQueryBuilder extends AbstractQueryBuilder<DisMaxQueryBuilder>
         for (QueryBuilder query : queries) {
             disMaxQuery.add(query);
         }
-        return Optional.of(disMaxQuery);
+        return disMaxQuery;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/ExistsQueryBuilder.java

@@ -37,7 +37,6 @@ import java.io.IOException;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Constructs a query that only match on documents that the field has a value in them.
@@ -84,7 +83,7 @@ public class ExistsQueryBuilder extends AbstractQueryBuilder<ExistsQueryBuilder>
         builder.endObject();
     }
 
-    public static Optional<ExistsQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static ExistsQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String fieldPattern = null;
@@ -120,7 +119,7 @@ public class ExistsQueryBuilder extends AbstractQueryBuilder<ExistsQueryBuilder>
         ExistsQueryBuilder builder = new ExistsQueryBuilder(fieldPattern);
         builder.queryName(queryName);
         builder.boost(boost);
-        return Optional.of(builder);
+        return builder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/FieldMaskingSpanQueryBuilder.java

@@ -33,7 +33,6 @@ import org.elasticsearch.index.mapper.MappedFieldType;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 public class FieldMaskingSpanQueryBuilder extends AbstractQueryBuilder<FieldMaskingSpanQueryBuilder> implements SpanQueryBuilder {
     public static final String NAME = "field_masking_span";
@@ -101,7 +100,7 @@ public class FieldMaskingSpanQueryBuilder extends AbstractQueryBuilder<FieldMask
         builder.endObject();
     }
 
-    public static Optional<FieldMaskingSpanQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static FieldMaskingSpanQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
@@ -117,11 +116,11 @@ public class FieldMaskingSpanQueryBuilder extends AbstractQueryBuilder<FieldMask
                 currentFieldName = parser.currentName();
             } else if (token == XContentParser.Token.START_OBJECT) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, QUERY_FIELD)) {
-                    Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                    QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                    if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                    if (query instanceof SpanQueryBuilder == false) {
                         throw new ParsingException(parser.getTokenLocation(), "[field_masking_span] query must be of type span query");
                     }
-                    inner = (SpanQueryBuilder) query.get();
+                    inner = (SpanQueryBuilder) query;
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), "[field_masking_span] query does not support ["
                             + currentFieldName + "]");
@@ -149,7 +148,7 @@ public class FieldMaskingSpanQueryBuilder extends AbstractQueryBuilder<FieldMask
         FieldMaskingSpanQueryBuilder queryBuilder = new FieldMaskingSpanQueryBuilder(inner, field);
         queryBuilder.boost(boost);
         queryBuilder.queryName(queryName);
-        return Optional.of(queryBuilder);
+        return queryBuilder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/FuzzyQueryBuilder.java

@@ -37,7 +37,6 @@ import org.elasticsearch.index.query.support.QueryParsers;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * A Query that does fuzzy matching for a specific value.
@@ -252,7 +251,7 @@ public class FuzzyQueryBuilder extends AbstractQueryBuilder<FuzzyQueryBuilder> i
         builder.endObject();
     }
 
-    public static Optional<FuzzyQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static FuzzyQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         String fieldName = null;
         Object value = null;
@@ -307,14 +306,14 @@ public class FuzzyQueryBuilder extends AbstractQueryBuilder<FuzzyQueryBuilder> i
                 value = parser.objectBytes();
             }
         }
-        return Optional.of(new FuzzyQueryBuilder(fieldName, value)
+        return new FuzzyQueryBuilder(fieldName, value)
                 .fuzziness(fuzziness)
                 .prefixLength(prefixLength)
                 .maxExpansions(maxExpansions)
                 .transpositions(transpositions)
                 .rewrite(rewrite)
                 .boost(boost)
-                .queryName(queryName));
+                .queryName(queryName);
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/GeoBoundingBoxQueryBuilder.java

@@ -40,7 +40,6 @@ import org.elasticsearch.index.mapper.MappedFieldType;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Creates a Lucene query that will filter for all documents that lie within the specified
@@ -374,7 +373,7 @@ public class GeoBoundingBoxQueryBuilder extends AbstractQueryBuilder<GeoBounding
         builder.endObject();
     }
 
-    public static Optional<GeoBoundingBoxQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static GeoBoundingBoxQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String fieldName = null;
@@ -485,7 +484,7 @@ public class GeoBoundingBoxQueryBuilder extends AbstractQueryBuilder<GeoBounding
         } else {
             builder.setValidationMethod(GeoValidationMethod.infer(coerce, ignoreMalformed));
         }
-        return Optional.of(builder);
+        return builder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/GeoDistanceQueryBuilder.java

@@ -40,7 +40,6 @@ import org.elasticsearch.index.mapper.MappedFieldType;
 import java.io.IOException;
 import java.util.Locale;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Filter results of a query to include only those within a specific distance to some
@@ -310,7 +309,7 @@ public class GeoDistanceQueryBuilder extends AbstractQueryBuilder<GeoDistanceQue
         builder.endObject();
     }
 
-    public static Optional<GeoDistanceQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static GeoDistanceQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         XContentParser.Token token;
@@ -425,7 +424,7 @@ public class GeoDistanceQueryBuilder extends AbstractQueryBuilder<GeoDistanceQue
         qb.boost(boost);
         qb.queryName(queryName);
         qb.ignoreUnmapped(ignoreUnmapped);
-        return Optional.of(qb);
+        return qb;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/GeoPolygonQueryBuilder.java

@@ -40,7 +40,6 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
-import java.util.Optional;
 
 public class GeoPolygonQueryBuilder extends AbstractQueryBuilder<GeoPolygonQueryBuilder> {
     public static final String NAME = "geo_polygon";
@@ -227,7 +226,7 @@ public class GeoPolygonQueryBuilder extends AbstractQueryBuilder<GeoPolygonQuery
         builder.endObject();
     }
 
-    public static Optional<GeoPolygonQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static GeoPolygonQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String fieldName = null;
@@ -308,7 +307,7 @@ public class GeoPolygonQueryBuilder extends AbstractQueryBuilder<GeoPolygonQuery
             builder.boost(boost);
         }
         builder.ignoreUnmapped(ignoreUnmapped);
-        return Optional.of(builder);
+        return builder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/GeoShapeQueryBuilder.java

@@ -47,7 +47,6 @@ import org.elasticsearch.index.mapper.MappedFieldType;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * {@link QueryBuilder} that builds a GeoShape Query
@@ -456,7 +455,7 @@ public class GeoShapeQueryBuilder extends AbstractQueryBuilder<GeoShapeQueryBuil
         builder.endObject();
     }
 
-    public static Optional<GeoShapeQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static GeoShapeQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String fieldName = null;
@@ -562,7 +561,7 @@ public class GeoShapeQueryBuilder extends AbstractQueryBuilder<GeoShapeQueryBuil
         }
         builder.boost(boost);
         builder.ignoreUnmapped(ignoreUnmapped);
-        return Optional.of(builder);
+        return builder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/HasChildQueryBuilder.java

@@ -43,7 +43,6 @@ import java.io.IOException;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * A query builder for <tt>has_child</tt> query.
@@ -222,7 +221,7 @@ public class HasChildQueryBuilder extends AbstractQueryBuilder<HasChildQueryBuil
         builder.endObject();
     }
 
-    public static Optional<HasChildQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static HasChildQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
         String childType = null;
@@ -234,7 +233,7 @@ public class HasChildQueryBuilder extends AbstractQueryBuilder<HasChildQueryBuil
         InnerHitBuilder innerHitBuilder = null;
         String currentFieldName = null;
         XContentParser.Token token;
-        Optional<QueryBuilder> iqb = Optional.empty();
+        QueryBuilder iqb = null;
         while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
             if (token == XContentParser.Token.FIELD_NAME) {
                 currentFieldName = parser.currentName();
@@ -268,13 +267,7 @@ public class HasChildQueryBuilder extends AbstractQueryBuilder<HasChildQueryBuil
                 }
             }
         }
-
+        HasChildQueryBuilder hasChildQueryBuilder = new HasChildQueryBuilder(childType, iqb, scoreMode);
-        if (iqb.isPresent() == false) {
-            // if inner query is empty, bubble this up to caller so they can decide how to deal with it
-            return Optional.empty();
-        }
-
-        HasChildQueryBuilder hasChildQueryBuilder = new HasChildQueryBuilder(childType, iqb.get(), scoreMode);
         if (innerHitBuilder != null) {
             hasChildQueryBuilder.innerHit(innerHitBuilder);
         }
@@ -282,7 +275,7 @@ public class HasChildQueryBuilder extends AbstractQueryBuilder<HasChildQueryBuil
         hasChildQueryBuilder.queryName(queryName);
         hasChildQueryBuilder.boost(boost);
         hasChildQueryBuilder.ignoreUnmapped(ignoreUnmapped);
-        return Optional.of(hasChildQueryBuilder);
+        return hasChildQueryBuilder;
     }
 
     public static ScoreMode parseScoreMode(String scoreModeString) {

core/src/main/java/org/elasticsearch/index/query/HasParentQueryBuilder.java

@@ -38,7 +38,6 @@ import java.io.IOException;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.Set;
 
 /**
@@ -223,7 +222,7 @@ public class HasParentQueryBuilder extends AbstractQueryBuilder<HasParentQueryBu
         builder.endObject();
     }
 
-    public static Optional<HasParentQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static HasParentQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
         String parentType = null;
@@ -234,7 +233,7 @@ public class HasParentQueryBuilder extends AbstractQueryBuilder<HasParentQueryBu
 
         String currentFieldName = null;
         XContentParser.Token token;
-        Optional<QueryBuilder> iqb = Optional.empty();
+        QueryBuilder iqb = null;
         while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
             if (token == XContentParser.Token.FIELD_NAME) {
                 currentFieldName = parser.currentName();
@@ -272,18 +271,14 @@ public class HasParentQueryBuilder extends AbstractQueryBuilder<HasParentQueryBu
                 }
             }
         }
-        if (iqb.isPresent() == false) {
+        HasParentQueryBuilder queryBuilder =  new HasParentQueryBuilder(parentType, iqb, score)
-            // if inner query is empty, bubble this up to caller so they can decide how to deal with it
-            return Optional.empty();
-        }
-        HasParentQueryBuilder queryBuilder =  new HasParentQueryBuilder(parentType, iqb.get(), score)
                 .ignoreUnmapped(ignoreUnmapped)
                 .queryName(queryName)
                 .boost(boost);
         if (innerHits != null) {
             queryBuilder.innerHit(innerHits);
         }
-        return Optional.of(queryBuilder);
+        return queryBuilder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/IdsQueryBuilder.java

@@ -39,7 +39,6 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.Set;
 
 import static org.elasticsearch.common.xcontent.ObjectParser.fromList;
@@ -146,9 +145,9 @@ public class IdsQueryBuilder extends AbstractQueryBuilder<IdsQueryBuilder> {
         declareStandardFields(PARSER);
     }
 
-    public static Optional<IdsQueryBuilder> fromXContent(QueryParseContext context) {
+    public static IdsQueryBuilder fromXContent(QueryParseContext context) {
         try {
-            return Optional.of(PARSER.apply(context.parser(), context));
+            return PARSER.apply(context.parser(), context);
         } catch (IllegalArgumentException e) {
             throw new ParsingException(context.parser().getTokenLocation(), e.getMessage(), e);
         }

core/src/main/java/org/elasticsearch/index/query/MatchAllQueryBuilder.java

@@ -64,9 +64,9 @@ public class MatchAllQueryBuilder extends AbstractQueryBuilder<MatchAllQueryBuil
         declareStandardFields(PARSER);
     }
 
-    public static Optional<MatchAllQueryBuilder> fromXContent(QueryParseContext context) {
+    public static MatchAllQueryBuilder fromXContent(QueryParseContext context) {
         try {
-            return Optional.of(PARSER.apply(context.parser(), context));
+            return PARSER.apply(context.parser(), context);
         } catch (IllegalArgumentException e) {
             throw new ParsingException(context.parser().getTokenLocation(), e.getMessage(), e);
         }

core/src/main/java/org/elasticsearch/index/query/MatchNoneQueryBuilder.java

@@ -28,7 +28,6 @@ import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
-import java.util.Optional;
 
 /**
  * A query that matches no document.
@@ -58,7 +57,7 @@ public class MatchNoneQueryBuilder extends AbstractQueryBuilder<MatchNoneQueryBu
         builder.endObject();
     }
 
-    public static Optional<MatchNoneQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static MatchNoneQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String currentFieldName = null;
@@ -86,7 +85,7 @@ public class MatchNoneQueryBuilder extends AbstractQueryBuilder<MatchNoneQueryBu
         MatchNoneQueryBuilder matchNoneQueryBuilder = new MatchNoneQueryBuilder();
         matchNoneQueryBuilder.boost(boost);
         matchNoneQueryBuilder.queryName(queryName);
-        return Optional.of(matchNoneQueryBuilder);
+        return matchNoneQueryBuilder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/MatchPhrasePrefixQueryBuilder.java

@@ -31,7 +31,6 @@ import org.elasticsearch.index.search.MatchQuery;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Match query is a query that analyzes the text and constructs a phrase prefix
@@ -190,7 +189,7 @@ public class MatchPhrasePrefixQueryBuilder extends AbstractQueryBuilder<MatchPhr
         return Objects.hash(fieldName, value, analyzer, slop, maxExpansions);
     }
 
-    public static Optional<MatchPhrasePrefixQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static MatchPhrasePrefixQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         String fieldName = null;
         Object value = null;
@@ -247,6 +246,6 @@ public class MatchPhrasePrefixQueryBuilder extends AbstractQueryBuilder<MatchPhr
         matchQuery.maxExpansions(maxExpansion);
         matchQuery.queryName(queryName);
         matchQuery.boost(boost);
-        return Optional.of(matchQuery);
+        return matchQuery;
     }
 }

core/src/main/java/org/elasticsearch/index/query/MatchPhraseQueryBuilder.java

@@ -31,7 +31,6 @@ import org.elasticsearch.index.search.MatchQuery;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Match query is a query that analyzes the text and constructs a phrase query
@@ -162,7 +161,7 @@ public class MatchPhraseQueryBuilder extends AbstractQueryBuilder<MatchPhraseQue
         return Objects.hash(fieldName, value, analyzer, slop);
     }
 
-    public static Optional<MatchPhraseQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static MatchPhraseQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         String fieldName = null;
         Object value = null;
@@ -215,6 +214,6 @@ public class MatchPhraseQueryBuilder extends AbstractQueryBuilder<MatchPhraseQue
         matchQuery.slop(slop);
         matchQuery.queryName(queryName);
         matchQuery.boost(boost);
-        return Optional.of(matchQuery);
+        return matchQuery;
     }
 }

core/src/main/java/org/elasticsearch/index/query/MatchQueryBuilder.java

@@ -40,7 +40,6 @@ import java.io.IOException;
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Match query is a query that analyzes the text and constructs a query as the
@@ -524,7 +523,7 @@ public class MatchQueryBuilder extends AbstractQueryBuilder<MatchQueryBuilder> {
         return NAME;
     }
 
-    public static Optional<MatchQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static MatchQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         String fieldName = null;
         MatchQuery.Type type = MatchQuery.Type.BOOLEAN;
@@ -646,7 +645,7 @@ public class MatchQueryBuilder extends AbstractQueryBuilder<MatchQueryBuilder> {
         matchQuery.zeroTermsQuery(zeroTermsQuery);
         matchQuery.queryName(queryName);
         matchQuery.boost(boost);
-        return Optional.of(matchQuery);
+        return matchQuery;
     }
 
 }

core/src/main/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilder.java

@@ -802,7 +802,7 @@ public class MoreLikeThisQueryBuilder extends AbstractQueryBuilder<MoreLikeThisQ
         builder.endObject();
     }
 
-    public static Optional<MoreLikeThisQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static MoreLikeThisQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         // document inputs
@@ -952,7 +952,7 @@ public class MoreLikeThisQueryBuilder extends AbstractQueryBuilder<MoreLikeThisQ
         if (stopWords != null) {
             moreLikeThisQueryBuilder.stopWords(stopWords);
         }
-        return Optional.of(moreLikeThisQueryBuilder);
+        return moreLikeThisQueryBuilder;
     }
 
     private static void parseLikeField(QueryParseContext parseContext, List<String> texts, List<Item> items) throws IOException {

core/src/main/java/org/elasticsearch/index/query/MultiMatchQueryBuilder.java

@@ -556,7 +556,7 @@ public class MultiMatchQueryBuilder extends AbstractQueryBuilder<MultiMatchQuery
         builder.endObject();
     }
 
-    public static Optional<MultiMatchQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static MultiMatchQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         Object value = null;
@@ -660,7 +660,7 @@ public class MultiMatchQueryBuilder extends AbstractQueryBuilder<MultiMatchQuery
                     "Fuziness not allowed for type [" + type.parseField.getPreferredName() + "]");
         }
 
-        return Optional.of(new MultiMatchQueryBuilder(value)
+        return new MultiMatchQueryBuilder(value)
                 .fields(fieldsBoosts)
                 .type(type)
                 .analyzer(analyzer)
@@ -677,7 +677,7 @@ public class MultiMatchQueryBuilder extends AbstractQueryBuilder<MultiMatchQuery
                 .tieBreaker(tieBreaker)
                 .zeroTermsQuery(zeroTermsQuery)
                 .boost(boost)
-                .queryName(queryName));
+                .queryName(queryName);
     }
 
     private static void parseFieldAndBoost(XContentParser parser, Map<String, Float> fieldsBoosts) throws IOException {

core/src/main/java/org/elasticsearch/index/query/NestedQueryBuilder.java

@@ -36,7 +36,6 @@ import org.elasticsearch.index.mapper.ObjectMapper;
 import java.io.IOException;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 
 public class NestedQueryBuilder extends AbstractQueryBuilder<NestedQueryBuilder> {
     public static final String NAME = "nested";
@@ -152,12 +151,12 @@ public class NestedQueryBuilder extends AbstractQueryBuilder<NestedQueryBuilder>
         builder.endObject();
     }
 
-    public static Optional<NestedQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static NestedQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
         ScoreMode scoreMode = ScoreMode.Avg;
         String queryName = null;
-        Optional<QueryBuilder> query = Optional.empty();
+        QueryBuilder query = null;
         String path = null;
         String currentFieldName = null;
         InnerHitBuilder innerHitBuilder = null;
@@ -190,19 +189,14 @@ public class NestedQueryBuilder extends AbstractQueryBuilder<NestedQueryBuilder>
                 }
             }
         }
-
+        NestedQueryBuilder queryBuilder =  new NestedQueryBuilder(path, query, scoreMode)
-        if (query.isPresent() == false) {
-            // if inner query is empty, bubble this up to caller so they can decide how to deal with it
-            return Optional.empty();
-        }
-        NestedQueryBuilder queryBuilder =  new NestedQueryBuilder(path, query.get(), scoreMode)
                 .ignoreUnmapped(ignoreUnmapped)
                 .queryName(queryName)
                 .boost(boost);
         if (innerHitBuilder != null) {
             queryBuilder.innerHit(innerHitBuilder);
         }
-        return Optional.of(queryBuilder);
+        return queryBuilder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/ParentIdQueryBuilder.java

@@ -38,7 +38,6 @@ import org.elasticsearch.index.mapper.TypeFieldMapper;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 public final class ParentIdQueryBuilder extends AbstractQueryBuilder<ParentIdQueryBuilder> {
     public static final String NAME = "parent_id";
@@ -116,7 +115,7 @@ public final class ParentIdQueryBuilder extends AbstractQueryBuilder<ParentIdQue
         builder.endObject();
     }
 
-    public static Optional<ParentIdQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static ParentIdQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
         String type = null;
@@ -150,7 +149,7 @@ public final class ParentIdQueryBuilder extends AbstractQueryBuilder<ParentIdQue
         queryBuilder.queryName(queryName);
         queryBuilder.boost(boost);
         queryBuilder.ignoreUnmapped(ignoreUnmapped);
-        return Optional.of(queryBuilder);
+        return queryBuilder;
     }
 
 

core/src/main/java/org/elasticsearch/index/query/PrefixQueryBuilder.java

@@ -36,7 +36,6 @@ import org.elasticsearch.index.query.support.QueryParsers;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * A Query that matches documents containing terms with a specified prefix.
@@ -117,7 +116,7 @@ public class PrefixQueryBuilder extends AbstractQueryBuilder<PrefixQueryBuilder>
         builder.endObject();
     }
 
-    public static Optional<PrefixQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static PrefixQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String fieldName = null;
@@ -161,10 +160,10 @@ public class PrefixQueryBuilder extends AbstractQueryBuilder<PrefixQueryBuilder>
             }
         }
 
-        return Optional.of(new PrefixQueryBuilder(fieldName, value)
+        return new PrefixQueryBuilder(fieldName, value)
                 .rewrite(rewrite)
                 .boost(boost)
-                .queryName(queryName));
+                .queryName(queryName);
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/QueryParseContext.java

@@ -23,20 +23,15 @@ import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.common.ParseFieldMatcherSupplier;
 import org.elasticsearch.common.ParsingException;
-import org.elasticsearch.common.logging.DeprecationLogger;
-import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.indices.query.IndicesQueriesRegistry;
 import org.elasticsearch.script.Script;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 public class QueryParseContext implements ParseFieldMatcherSupplier {
 
-    private static final DeprecationLogger DEPRECATION_LOGGER = new DeprecationLogger(Loggers.getLogger(QueryParseContext.class));
-
     private static final ParseField CACHE = new ParseField("_cache").withAllDeprecated("Elasticsearch makes its own caching decisions");
     private static final ParseField CACHE_KEY = new ParseField("_cache_key").withAllDeprecated("Filters are always used as cache keys");
 
@@ -75,7 +70,7 @@ public class QueryParseContext implements ParseFieldMatcherSupplier {
                 if (token == XContentParser.Token.FIELD_NAME) {
                     String fieldName = parser.currentName();
                     if ("query".equals(fieldName)) {
-                        queryBuilder = parseInnerQueryBuilder().orElse(null);
+                        queryBuilder = parseInnerQueryBuilder();
                     } else {
                         throw new ParsingException(parser.getTokenLocation(), "request does not support [" + parser.currentName() + "]");
                     }
@@ -92,20 +87,15 @@ public class QueryParseContext implements ParseFieldMatcherSupplier {
     /**
      * Parses a query excluding the query element that wraps it
      */
-    public Optional<QueryBuilder> parseInnerQueryBuilder() throws IOException {
+    public QueryBuilder parseInnerQueryBuilder() throws IOException {
         if (parser.currentToken() != XContentParser.Token.START_OBJECT) {
             if (parser.nextToken() != XContentParser.Token.START_OBJECT) {
                 throw new ParsingException(parser.getTokenLocation(), "[_na] query malformed, must start with start_object");
             }
         }
         if (parser.nextToken() == XContentParser.Token.END_OBJECT) {
-            // we encountered '{}' for a query clause
+            // we encountered '{}' for a query clause, it used to be supported, deprecated in 5.0 and removed in 6.0
-            String msg = "query malformed, empty clause found at [" + parser.getTokenLocation() +"]";
+            throw new IllegalArgumentException("query malformed, empty clause found at [" + parser.getTokenLocation() +"]");
-            DEPRECATION_LOGGER.deprecated(msg);
-            if (parseFieldMatcher.isStrict()) {
-                throw new IllegalArgumentException(msg);
-            }
-            return Optional.empty();
         }
         if (parser.currentToken() != XContentParser.Token.FIELD_NAME) {
             throw new ParsingException(parser.getTokenLocation(), "[_na] query malformed, no field after start_object");
@@ -115,9 +105,7 @@ public class QueryParseContext implements ParseFieldMatcherSupplier {
         if (parser.nextToken() != XContentParser.Token.START_OBJECT) {
             throw new ParsingException(parser.getTokenLocation(), "[" + queryName + "] query malformed, no start_object after query name");
         }
-        @SuppressWarnings("unchecked")
+        QueryBuilder result = indicesQueriesRegistry.lookup(queryName, parseFieldMatcher, parser.getTokenLocation()).fromXContent(this);
-        Optional<QueryBuilder> result = (Optional<QueryBuilder>) indicesQueriesRegistry.lookup(queryName, parseFieldMatcher,
-                parser.getTokenLocation()).fromXContent(this);
         //end_object of the specific query (e.g. match, multi_match etc.) element
         if (parser.currentToken() != XContentParser.Token.END_OBJECT) {
             throw new ParsingException(parser.getTokenLocation(),

core/src/main/java/org/elasticsearch/index/query/QueryParser.java

@@ -20,7 +20,6 @@
 package org.elasticsearch.index.query;
 
 import java.io.IOException;
-import java.util.Optional;
 
 /**
  * Defines a query parser that is able to parse {@link QueryBuilder}s from {@link org.elasticsearch.common.xcontent.XContent}.
@@ -37,5 +36,5 @@ public interface QueryParser<QB extends QueryBuilder> {
      *            call
      * @return the new QueryBuilder
      */
-    Optional<QB> fromXContent(QueryParseContext parseContext) throws IOException;
+    QB fromXContent(QueryParseContext parseContext) throws IOException;
 }

core/src/main/java/org/elasticsearch/index/query/QueryStringQueryBuilder.java

@@ -57,7 +57,6 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.Set;
 import java.util.TreeMap;
 
@@ -685,7 +684,7 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
         builder.endObject();
     }
 
-    public static Optional<QueryStringQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static QueryStringQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         String currentFieldName = null;
         XContentParser.Token token;
@@ -855,7 +854,7 @@ public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQue
         queryStringQuery.queryName(queryName);
         queryStringQuery.splitOnWhitespace(splitOnWhitespace);
         queryStringQuery.useAllFields(useAllFields);
-        return Optional.of(queryStringQuery);
+        return queryStringQuery;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/RangeQueryBuilder.java

@@ -44,7 +44,6 @@ import org.joda.time.DateTimeZone;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * A Query that matches documents within an range of terms.
@@ -344,7 +343,7 @@ public class RangeQueryBuilder extends AbstractQueryBuilder<RangeQueryBuilder> i
         builder.endObject();
     }
 
-    public static Optional<RangeQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static RangeQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String fieldName = null;
@@ -435,7 +434,7 @@ public class RangeQueryBuilder extends AbstractQueryBuilder<RangeQueryBuilder> i
         if (relation != null) {
             rangeQuery.relation(relation);
         }
-        return Optional.of(rangeQuery);
+        return rangeQuery;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/RegexpQueryBuilder.java

@@ -37,7 +37,6 @@ import org.elasticsearch.index.query.support.QueryParsers;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * A Query that does fuzzy matching for a specific value.
@@ -178,7 +177,7 @@ public class RegexpQueryBuilder extends AbstractQueryBuilder<RegexpQueryBuilder>
         builder.endObject();
     }
 
-    public static Optional<RegexpQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static RegexpQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         String fieldName = null;
         String rewrite = null;
@@ -233,12 +232,12 @@ public class RegexpQueryBuilder extends AbstractQueryBuilder<RegexpQueryBuilder>
             }
         }
 
-        return Optional.of(new RegexpQueryBuilder(fieldName, value)
+        return new RegexpQueryBuilder(fieldName, value)
                 .flags(flagsValue)
                 .maxDeterminizedStates(maxDeterminizedStates)
                 .rewrite(rewrite)
                 .boost(boost)
-                .queryName(queryName));
+                .queryName(queryName);
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/ScriptQueryBuilder.java

@@ -38,7 +38,6 @@ import org.elasticsearch.script.SearchScript;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 public class ScriptQueryBuilder extends AbstractQueryBuilder<ScriptQueryBuilder> {
     public static final String NAME = "script";
@@ -84,7 +83,7 @@ public class ScriptQueryBuilder extends AbstractQueryBuilder<ScriptQueryBuilder>
         builder.endObject();
     }
 
-    public static Optional<ScriptQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static ScriptQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         // also, when caching, since its isCacheable is false, will result in loading all bit set...
         Script script = null;
@@ -122,9 +121,9 @@ public class ScriptQueryBuilder extends AbstractQueryBuilder<ScriptQueryBuilder>
             throw new ParsingException(parser.getTokenLocation(), "script must be provided with a [script] filter");
         }
 
-        return Optional.of(new ScriptQueryBuilder(script)
+        return new ScriptQueryBuilder(script)
                 .boost(boost)
-                .queryName(queryName));
+                .queryName(queryName);
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/SimpleQueryStringBuilder.java

@@ -40,7 +40,6 @@ import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.TreeMap;
 
 /**
@@ -471,7 +470,7 @@ public class SimpleQueryStringBuilder extends AbstractQueryBuilder<SimpleQuerySt
         builder.endObject();
     }
 
-    public static Optional<SimpleQueryStringBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static SimpleQueryStringBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String currentFieldName = null;
@@ -580,7 +579,7 @@ public class SimpleQueryStringBuilder extends AbstractQueryBuilder<SimpleQuerySt
         }
         qb.analyzeWildcard(analyzeWildcard).boost(boost).quoteFieldSuffix(quoteFieldSuffix);
         qb.useAllFields(useAllFields);
-        return Optional.of(qb);
+        return qb;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/SpanContainingQueryBuilder.java

@@ -31,7 +31,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Builder for {@link org.apache.lucene.search.spans.SpanContainingQuery}.
@@ -100,7 +99,7 @@ public class SpanContainingQueryBuilder extends AbstractQueryBuilder<SpanContain
         builder.endObject();
     }
 
-    public static Optional<SpanContainingQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static SpanContainingQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
         String queryName = null;
@@ -114,17 +113,17 @@ public class SpanContainingQueryBuilder extends AbstractQueryBuilder<SpanContain
                 currentFieldName = parser.currentName();
             } else if (token == XContentParser.Token.START_OBJECT) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, BIG_FIELD)) {
-                    Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                    QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                    if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                    if (query instanceof SpanQueryBuilder == false) {
                         throw new ParsingException(parser.getTokenLocation(), "span_containing [big] must be of type span query");
                     }
-                    big = (SpanQueryBuilder) query.get();
+                    big = (SpanQueryBuilder) query;
                 } else if (parseContext.getParseFieldMatcher().match(currentFieldName, LITTLE_FIELD)) {
-                    Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                    QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                    if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                    if (query instanceof SpanQueryBuilder == false) {
                         throw new ParsingException(parser.getTokenLocation(), "span_containing [little] must be of type span query");
                     }
-                    little = (SpanQueryBuilder) query.get();
+                    little = (SpanQueryBuilder) query;
                 } else {
                     throw new ParsingException(parser.getTokenLocation(),
                             "[span_containing] query does not support [" + currentFieldName + "]");
@@ -141,7 +140,7 @@ public class SpanContainingQueryBuilder extends AbstractQueryBuilder<SpanContain
 
         SpanContainingQueryBuilder query = new SpanContainingQueryBuilder(big, little);
         query.boost(boost).queryName(queryName);
-        return Optional.of(query);
+        return query;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/SpanFirstQueryBuilder.java

@@ -31,7 +31,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 public class SpanFirstQueryBuilder extends AbstractQueryBuilder<SpanFirstQueryBuilder> implements SpanQueryBuilder {
     public static final String NAME = "span_first";
@@ -100,7 +99,7 @@ public class SpanFirstQueryBuilder extends AbstractQueryBuilder<SpanFirstQueryBu
         builder.endObject();
     }
 
-    public static Optional<SpanFirstQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static SpanFirstQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
@@ -116,11 +115,11 @@ public class SpanFirstQueryBuilder extends AbstractQueryBuilder<SpanFirstQueryBu
                 currentFieldName = parser.currentName();
             } else if (token == XContentParser.Token.START_OBJECT) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, MATCH_FIELD)) {
-                    Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                    QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                    if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                    if (query instanceof SpanQueryBuilder == false) {
                         throw new ParsingException(parser.getTokenLocation(), "spanFirst [match] must be of type span query");
                     }
-                    match = (SpanQueryBuilder) query.get();
+                    match = (SpanQueryBuilder) query;
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), "[span_first] query does not support [" + currentFieldName + "]");
                 }
@@ -144,7 +143,7 @@ public class SpanFirstQueryBuilder extends AbstractQueryBuilder<SpanFirstQueryBu
         }
         SpanFirstQueryBuilder queryBuilder = new SpanFirstQueryBuilder(match, end);
         queryBuilder.boost(boost).queryName(queryName);
-        return Optional.of(queryBuilder);
+        return queryBuilder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/SpanMultiTermQueryBuilder.java

@@ -33,7 +33,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Query that allows wraping a {@link MultiTermQueryBuilder} (one of wildcard, fuzzy, prefix, term, range or regexp query)
@@ -82,7 +81,7 @@ public class SpanMultiTermQueryBuilder extends AbstractQueryBuilder<SpanMultiTer
         builder.endObject();
     }
 
-    public static Optional<SpanMultiTermQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static SpanMultiTermQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         String currentFieldName = null;
         MultiTermQueryBuilder subQuery = null;
@@ -94,12 +93,12 @@ public class SpanMultiTermQueryBuilder extends AbstractQueryBuilder<SpanMultiTer
                 currentFieldName = parser.currentName();
             } else if (token == XContentParser.Token.START_OBJECT) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, MATCH_FIELD)) {
-                    Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                    QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                    if (query.isPresent() == false || query.get() instanceof MultiTermQueryBuilder == false) {
+                    if (query instanceof MultiTermQueryBuilder == false) {
                         throw new ParsingException(parser.getTokenLocation(),
                                 "[span_multi] [" + MATCH_FIELD.getPreferredName() + "] must be of type multi term query");
                     }
-                    subQuery = (MultiTermQueryBuilder) query.get();
+                    subQuery = (MultiTermQueryBuilder) query;
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), "[span_multi] query does not support [" + currentFieldName + "]");
                 }
@@ -119,7 +118,7 @@ public class SpanMultiTermQueryBuilder extends AbstractQueryBuilder<SpanMultiTer
                     "[span_multi] must have [" + MATCH_FIELD.getPreferredName() + "] multi term query clause");
         }
 
-        return Optional.of(new SpanMultiTermQueryBuilder(subQuery).queryName(queryName).boost(boost));
+        return new SpanMultiTermQueryBuilder(subQuery).queryName(queryName).boost(boost);
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/SpanNearQueryBuilder.java

@@ -34,7 +34,6 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Matches spans which are near one another. One can specify slop, the maximum number
@@ -144,7 +143,7 @@ public class SpanNearQueryBuilder extends AbstractQueryBuilder<SpanNearQueryBuil
         builder.endObject();
     }
 
-    public static Optional<SpanNearQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static SpanNearQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
@@ -162,11 +161,11 @@ public class SpanNearQueryBuilder extends AbstractQueryBuilder<SpanNearQueryBuil
             } else if (token == XContentParser.Token.START_ARRAY) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, CLAUSES_FIELD)) {
                     while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
-                        Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                        QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                        if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                        if (query instanceof SpanQueryBuilder == false) {
                             throw new ParsingException(parser.getTokenLocation(), "spanNear [clauses] must be of type span query");
                         }
-                        clauses.add((SpanQueryBuilder) query.get());
+                        clauses.add((SpanQueryBuilder) query);
                     }
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), "[span_near] query does not support [" + currentFieldName + "]");
@@ -203,7 +202,7 @@ public class SpanNearQueryBuilder extends AbstractQueryBuilder<SpanNearQueryBuil
         queryBuilder.inOrder(inOrder);
         queryBuilder.boost(boost);
         queryBuilder.queryName(queryName);
-        return Optional.of(queryBuilder);
+        return queryBuilder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/SpanNotQueryBuilder.java

@@ -31,7 +31,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 public class SpanNotQueryBuilder extends AbstractQueryBuilder<SpanNotQueryBuilder> implements SpanQueryBuilder {
     public static final String NAME = "span_not";
@@ -161,7 +160,7 @@ public class SpanNotQueryBuilder extends AbstractQueryBuilder<SpanNotQueryBuilde
         builder.endObject();
     }
 
-    public static Optional<SpanNotQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static SpanNotQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
@@ -182,17 +181,17 @@ public class SpanNotQueryBuilder extends AbstractQueryBuilder<SpanNotQueryBuilde
                 currentFieldName = parser.currentName();
             } else if (token == XContentParser.Token.START_OBJECT) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, INCLUDE_FIELD)) {
-                    Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                    QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                    if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                    if (query instanceof SpanQueryBuilder == false) {
                         throw new ParsingException(parser.getTokenLocation(), "spanNot [include] must be of type span query");
                     }
-                    include = (SpanQueryBuilder) query.get();
+                    include = (SpanQueryBuilder) query;
                 } else if (parseContext.getParseFieldMatcher().match(currentFieldName, EXCLUDE_FIELD)) {
-                    Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                    QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                    if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                    if (query instanceof SpanQueryBuilder == false) {
                         throw new ParsingException(parser.getTokenLocation(), "spanNot [exclude] must be of type span query");
                     }
-                    exclude = (SpanQueryBuilder) query.get();
+                    exclude = (SpanQueryBuilder) query;
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), "[span_not] query does not support [" + currentFieldName + "]");
                 }
@@ -234,7 +233,7 @@ public class SpanNotQueryBuilder extends AbstractQueryBuilder<SpanNotQueryBuilde
         }
         spanNotQuery.boost(boost);
         spanNotQuery.queryName(queryName);
-        return Optional.of(spanNotQuery);
+        return spanNotQuery;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/SpanOrQueryBuilder.java

@@ -34,7 +34,6 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Span query that matches the union of its clauses. Maps to {@link SpanOrQuery}.
@@ -98,7 +97,7 @@ public class SpanOrQueryBuilder extends AbstractQueryBuilder<SpanOrQueryBuilder>
         builder.endObject();
     }
 
-    public static Optional<SpanOrQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static SpanOrQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
@@ -114,11 +113,11 @@ public class SpanOrQueryBuilder extends AbstractQueryBuilder<SpanOrQueryBuilder>
             } else if (token == XContentParser.Token.START_ARRAY) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, CLAUSES_FIELD)) {
                     while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
-                        Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                        QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                        if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                        if (query instanceof SpanQueryBuilder == false) {
                             throw new ParsingException(parser.getTokenLocation(), "spanOr [clauses] must be of type span query");
                         }
-                        clauses.add((SpanQueryBuilder) query.get());
+                        clauses.add((SpanQueryBuilder) query);
                     }
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), "[span_or] query does not support [" + currentFieldName + "]");
@@ -144,7 +143,7 @@ public class SpanOrQueryBuilder extends AbstractQueryBuilder<SpanOrQueryBuilder>
         }
         queryBuilder.boost(boost);
         queryBuilder.queryName(queryName);
-        return Optional.of(queryBuilder);
+        return queryBuilder;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/SpanTermQueryBuilder.java

@@ -31,7 +31,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.mapper.MappedFieldType;
 
 import java.io.IOException;
-import java.util.Optional;
 
 /**
  * A Span Query that matches documents containing a term.
@@ -92,7 +91,7 @@ public class SpanTermQueryBuilder extends BaseTermQueryBuilder<SpanTermQueryBuil
         return new SpanTermQuery(term);
     }
 
-    public static Optional<SpanTermQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException, ParsingException {
+    public static SpanTermQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException, ParsingException {
         XContentParser parser = parseContext.parser();
         String fieldName = null;
         Object value = null;
@@ -133,7 +132,7 @@ public class SpanTermQueryBuilder extends BaseTermQueryBuilder<SpanTermQueryBuil
 
         SpanTermQueryBuilder result = new SpanTermQueryBuilder(fieldName, value);
         result.boost(boost).queryName(queryName);
-        return Optional.of(result);
+        return result;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/SpanWithinQueryBuilder.java

@@ -31,7 +31,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Builder for {@link org.apache.lucene.search.spans.SpanWithinQuery}.
@@ -105,7 +104,7 @@ public class SpanWithinQueryBuilder extends AbstractQueryBuilder<SpanWithinQuery
         builder.endObject();
     }
 
-    public static Optional<SpanWithinQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static SpanWithinQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
@@ -120,17 +119,17 @@ public class SpanWithinQueryBuilder extends AbstractQueryBuilder<SpanWithinQuery
                 currentFieldName = parser.currentName();
             } else if (token == XContentParser.Token.START_OBJECT) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, BIG_FIELD)) {
-                    Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                    QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                    if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                    if (query instanceof SpanQueryBuilder == false) {
                         throw new ParsingException(parser.getTokenLocation(), "span_within [big] must be of type span query");
                     }
-                    big = (SpanQueryBuilder) query.get();
+                    big = (SpanQueryBuilder) query;
                 } else if (parseContext.getParseFieldMatcher().match(currentFieldName, LITTLE_FIELD)) {
-                    Optional<QueryBuilder> query = parseContext.parseInnerQueryBuilder();
+                    QueryBuilder query = parseContext.parseInnerQueryBuilder();
-                    if (query.isPresent() == false || query.get() instanceof SpanQueryBuilder == false) {
+                    if (query instanceof SpanQueryBuilder == false) {
                         throw new ParsingException(parser.getTokenLocation(), "span_within [little] must be of type span query");
                     }
-                    little = (SpanQueryBuilder) query.get();
+                    little = (SpanQueryBuilder) query;
                 } else {
                     throw new ParsingException(parser.getTokenLocation(),
                             "[span_within] query does not support [" + currentFieldName + "]");
@@ -153,7 +152,7 @@ public class SpanWithinQueryBuilder extends AbstractQueryBuilder<SpanWithinQuery
 
         SpanWithinQueryBuilder query = new SpanWithinQueryBuilder(big, little);
         query.boost(boost).queryName(queryName);
-        return Optional.of(query);
+        return query;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/TermQueryBuilder.java

@@ -30,7 +30,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.mapper.MappedFieldType;
 
 import java.io.IOException;
-import java.util.Optional;
 
 /**
  * A Query that matches documents containing a term.
@@ -83,7 +82,7 @@ public class TermQueryBuilder extends BaseTermQueryBuilder<TermQueryBuilder> {
         super(in);
     }
 
-    public static Optional<TermQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static TermQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String queryName = null;
@@ -132,7 +131,7 @@ public class TermQueryBuilder extends BaseTermQueryBuilder<TermQueryBuilder> {
         if (queryName != null) {
             termQuery.queryName(queryName);
         }
-        return Optional.of(termQuery);
+        return termQuery;
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/TermsQueryBuilder.java

@@ -48,7 +48,6 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
@@ -321,7 +320,7 @@ public class TermsQueryBuilder extends AbstractQueryBuilder<TermsQueryBuilder> {
         builder.endObject();
     }
 
-    public static Optional<TermsQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static TermsQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         String fieldName = null;
@@ -372,9 +371,9 @@ public class TermsQueryBuilder extends AbstractQueryBuilder<TermsQueryBuilder> {
             throw new ParsingException(parser.getTokenLocation(), "[" + TermsQueryBuilder.NAME + "] query requires a field name, " +
                     "followed by array of terms or a document lookup specification");
         }
-        return Optional.of(new TermsQueryBuilder(fieldName, values, termsLookup)
+        return new TermsQueryBuilder(fieldName, values, termsLookup)
                 .boost(boost)
-                .queryName(queryName));
+                .queryName(queryName);
     }
 
     private static List<Object> parseValues(XContentParser parser) throws IOException {

core/src/main/java/org/elasticsearch/index/query/TypeQueryBuilder.java

@@ -33,7 +33,6 @@ import org.elasticsearch.index.mapper.DocumentMapper;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 public class TypeQueryBuilder extends AbstractQueryBuilder<TypeQueryBuilder> {
     public static final String NAME = "type";
@@ -81,7 +80,7 @@ public class TypeQueryBuilder extends AbstractQueryBuilder<TypeQueryBuilder> {
         builder.endObject();
     }
 
-    public static Optional<TypeQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static TypeQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         BytesRef type = null;
 
@@ -114,9 +113,9 @@ public class TypeQueryBuilder extends AbstractQueryBuilder<TypeQueryBuilder> {
             throw new ParsingException(parser.getTokenLocation(),
                     "[" + TypeQueryBuilder.NAME + "] filter needs to be provided with a value for the type");
         }
-        return Optional.of(new TypeQueryBuilder(type)
+        return new TypeQueryBuilder(type)
                 .boost(boost)
-                .queryName(queryName));
+                .queryName(queryName);
     }
 
 

core/src/main/java/org/elasticsearch/index/query/WildcardQueryBuilder.java

@@ -36,7 +36,6 @@ import org.elasticsearch.index.query.support.QueryParsers;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Implements the wildcard search query. Supported wildcards are <tt>*</tt>, which
@@ -133,7 +132,7 @@ public class WildcardQueryBuilder extends AbstractQueryBuilder<WildcardQueryBuil
         builder.endObject();
     }
 
-    public static Optional<WildcardQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static WildcardQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         String fieldName = null;
         String rewrite = null;
@@ -177,10 +176,10 @@ public class WildcardQueryBuilder extends AbstractQueryBuilder<WildcardQueryBuil
             }
         }
 
-        return Optional.of(new WildcardQueryBuilder(fieldName, value)
+        return new WildcardQueryBuilder(fieldName, value)
                 .rewrite(rewrite)
                 .boost(boost)
-                .queryName(queryName));
+                .queryName(queryName);
     }
 
     @Override

core/src/main/java/org/elasticsearch/index/query/WrapperQueryBuilder.java

@@ -34,7 +34,6 @@ import org.elasticsearch.common.xcontent.XContentParser;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
-import java.util.Optional;
 
 /**
  * A Query builder which allows building a query given JSON string or binary data provided as input. This is useful when you want
@@ -116,7 +115,7 @@ public class WrapperQueryBuilder extends AbstractQueryBuilder<WrapperQueryBuilde
         builder.endObject();
     }
 
-    public static Optional<WrapperQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static WrapperQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
         XContentParser.Token token = parser.nextToken();
@@ -136,7 +135,7 @@ public class WrapperQueryBuilder extends AbstractQueryBuilder<WrapperQueryBuilde
         if (source == null) {
             throw new ParsingException(parser.getTokenLocation(), "wrapper query has no [query] specified");
         }
-        return Optional.of(new WrapperQueryBuilder(source));
+        return new WrapperQueryBuilder(source);
     }
 
     @Override
@@ -164,8 +163,7 @@ public class WrapperQueryBuilder extends AbstractQueryBuilder<WrapperQueryBuilde
         try (XContentParser qSourceParser = XContentFactory.xContent(source).createParser(source)) {
             QueryParseContext parseContext = context.newParseContext(qSourceParser);
 
-            final QueryBuilder queryBuilder = parseContext.parseInnerQueryBuilder().orElseThrow(
+            final QueryBuilder queryBuilder = parseContext.parseInnerQueryBuilder();
-                    () -> new ParsingException(qSourceParser.getTokenLocation(), "inner query cannot be empty"));
             if (boost() != DEFAULT_BOOST || queryName() != null) {
                 final BoolQueryBuilder boolQueryBuilder = new BoolQueryBuilder();
                 boolQueryBuilder.must(queryBuilder);

core/src/main/java/org/elasticsearch/index/query/functionscore/FunctionScoreQueryBuilder.java

@@ -40,7 +40,6 @@ import org.elasticsearch.index.query.AbstractQueryBuilder;
 import org.elasticsearch.index.query.InnerHitBuilder;
 import org.elasticsearch.index.query.MatchAllQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
-import org.elasticsearch.index.query.QueryBuilders;
 import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.index.query.QueryRewriteContext;
 import org.elasticsearch.index.query.QueryShardContext;
@@ -52,7 +51,6 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * A query that uses a filters with a script associated with them to compute the
@@ -437,7 +435,7 @@ public class FunctionScoreQueryBuilder extends AbstractQueryBuilder<FunctionScor
         InnerHitBuilder.extractInnerHits(query(), innerHits);
     }
 
-    public static Optional<FunctionScoreQueryBuilder> fromXContent(ParseFieldRegistry<ScoreFunctionParser<?>> scoreFunctionsRegistry,
+    public static FunctionScoreQueryBuilder fromXContent(ParseFieldRegistry<ScoreFunctionParser<?>> scoreFunctionsRegistry,
             QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
 
@@ -467,7 +465,7 @@ public class FunctionScoreQueryBuilder extends AbstractQueryBuilder<FunctionScor
                         throw new ParsingException(parser.getTokenLocation(), "failed to parse [{}] query. [query] is already defined.",
                                 NAME);
                     }
-                    query = parseContext.parseInnerQueryBuilder().orElse(QueryBuilders.matchAllQuery());
+                    query = parseContext.parseInnerQueryBuilder();
                 } else {
                     if (singleFunctionFound) {
                         throw new ParsingException(parser.getTokenLocation(),
@@ -555,7 +553,7 @@ public class FunctionScoreQueryBuilder extends AbstractQueryBuilder<FunctionScor
         }
         functionScoreQueryBuilder.boost(boost);
         functionScoreQueryBuilder.queryName(queryName);
-        return Optional.of(functionScoreQueryBuilder);
+        return functionScoreQueryBuilder;
     }
 
     private static void handleMisplacedFunctionsDeclaration(XContentLocation contentLocation, String errorString) {
@@ -583,7 +581,7 @@ public class FunctionScoreQueryBuilder extends AbstractQueryBuilder<FunctionScor
                         currentFieldName = parser.currentName();
                     } else if (token == XContentParser.Token.START_OBJECT) {
                         if (parseContext.getParseFieldMatcher().match(currentFieldName, FILTER_FIELD)) {
-                            filter = parseContext.parseInnerQueryBuilder().orElse(QueryBuilders.matchAllQuery());
+                            filter = parseContext.parseInnerQueryBuilder();
                         } else {
                             if (scoreFunction != null) {
                                 throw new ParsingException(parser.getTokenLocation(),

core/src/main/java/org/elasticsearch/search/aggregations/bucket/filter/FilterAggregationBuilder.java

@@ -22,7 +22,6 @@ package org.elasticsearch.search.aggregations.bucket.filter;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.xcontent.XContentBuilder;
-import org.elasticsearch.index.query.MatchAllQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.search.aggregations.AbstractAggregationBuilder;
@@ -86,7 +85,7 @@ public class FilterAggregationBuilder extends AbstractAggregationBuilder<FilterA
     }
 
     public static FilterAggregationBuilder parse(String aggregationName, QueryParseContext context) throws IOException {
-        QueryBuilder filter = context.parseInnerQueryBuilder().orElse(new MatchAllQueryBuilder());
+        QueryBuilder filter = context.parseInnerQueryBuilder();
         return new FilterAggregationBuilder(aggregationName, filter);
     }
 

core/src/main/java/org/elasticsearch/search/aggregations/bucket/filters/FiltersAggregationBuilder.java

@@ -29,8 +29,8 @@ import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.search.aggregations.AbstractAggregationBuilder;
 import org.elasticsearch.search.aggregations.AggregatorFactories.Builder;
-import org.elasticsearch.search.aggregations.InternalAggregation.Type;
 import org.elasticsearch.search.aggregations.AggregatorFactory;
+import org.elasticsearch.search.aggregations.InternalAggregation.Type;
 import org.elasticsearch.search.aggregations.bucket.filters.FiltersAggregator.KeyedFilter;
 import org.elasticsearch.search.aggregations.support.AggregationContext;
 
@@ -41,8 +41,6 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 
-import static org.elasticsearch.index.query.QueryBuilders.matchAllQuery;
-
 public class FiltersAggregationBuilder extends AbstractAggregationBuilder<FiltersAggregationBuilder> {
     public static final String NAME = "filters";
     private static final Type TYPE = new Type(NAME);
@@ -240,7 +238,7 @@ public class FiltersAggregationBuilder extends AbstractAggregationBuilder<Filter
                         if (token == XContentParser.Token.FIELD_NAME) {
                             key = parser.currentName();
                         } else {
-                            QueryBuilder filter = context.parseInnerQueryBuilder().orElse(matchAllQuery());
+                            QueryBuilder filter = context.parseInnerQueryBuilder();
                             keyedFilters.add(new FiltersAggregator.KeyedFilter(key, filter));
                         }
                     }
@@ -252,7 +250,7 @@ public class FiltersAggregationBuilder extends AbstractAggregationBuilder<Filter
                 if (context.getParseFieldMatcher().match(currentFieldName, FILTERS_FIELD)) {
                     nonKeyedFilters = new ArrayList<>();
                     while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
-                        QueryBuilder filter = context.parseInnerQueryBuilder().orElse(matchAllQuery());
+                        QueryBuilder filter = context.parseInnerQueryBuilder();
                         nonKeyedFilters.add(filter);
                     }
                 } else {

core/src/main/java/org/elasticsearch/search/aggregations/bucket/significant/SignificantTermsAggregationBuilder.java

@@ -77,7 +77,7 @@ public class SignificantTermsAggregationBuilder extends ValuesSourceAggregationB
 
         parser.declareString(SignificantTermsAggregationBuilder::executionHint, TermsAggregationBuilder.EXECUTION_HINT_FIELD_NAME);
 
-        parser.declareObject((b, v) -> { if (v.isPresent()) b.backgroundFilter(v.get()); },
+        parser.declareObject(SignificantTermsAggregationBuilder::backgroundFilter,
                 (p, context) -> context.parseInnerQueryBuilder(),
                 SignificantTermsAggregationBuilder.BACKGROUND_FILTER);
 

core/src/main/java/org/elasticsearch/search/builder/SearchSourceBuilder.java

@@ -991,9 +991,9 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
                 }
             } else if (token == XContentParser.Token.START_OBJECT) {
                 if (context.getParseFieldMatcher().match(currentFieldName, QUERY_FIELD)) {
-                    queryBuilder = context.parseInnerQueryBuilder().orElse(null);
+                    queryBuilder = context.parseInnerQueryBuilder();
                 } else if (context.getParseFieldMatcher().match(currentFieldName, POST_FILTER_FIELD)) {
-                    postQueryBuilder = context.parseInnerQueryBuilder().orElse(null);
+                    postQueryBuilder = context.parseInnerQueryBuilder();
                 } else if (context.getParseFieldMatcher().match(currentFieldName, _SOURCE_FIELD)) {
                     fetchSourceContext = FetchSourceContext.parse(context.parser());
                 } else if (context.getParseFieldMatcher().match(currentFieldName, SCRIPT_FIELDS_FIELD)) {

core/src/main/java/org/elasticsearch/search/fetch/subphase/highlight/AbstractHighlighterBuilder.java

@@ -539,7 +539,7 @@ public abstract class AbstractHighlighterBuilder<HB extends AbstractHighlighterB
         }, OPTIONS_FIELD);
         parser.declareObject(HB::highlightQuery, (XContentParser p, QueryParseContext c) -> {
             try {
-                return c.parseInnerQueryBuilder().orElse(null);
+                return c.parseInnerQueryBuilder();
             } catch (IOException e) {
                 throw new RuntimeException("Error parsing query", e);
             }

core/src/main/java/org/elasticsearch/search/internal/ShardSearchRequest.java

@@ -38,7 +38,6 @@ import org.elasticsearch.search.Scroll;
 import org.elasticsearch.search.builder.SearchSourceBuilder;
 
 import java.io.IOException;
-import java.util.Optional;
 import java.util.function.Function;
 
 /**
@@ -110,11 +109,7 @@ public interface ShardSearchRequest {
             try {
                 byte[] filterSource = alias.filter().uncompressed();
                 try (XContentParser parser = XContentFactory.xContent(filterSource).createParser(filterSource)) {
-                    Optional<QueryBuilder> innerQueryBuilder = contextFactory.apply(parser).parseInnerQueryBuilder();
+                    return contextFactory.apply(parser).parseInnerQueryBuilder();
-                    if (innerQueryBuilder.isPresent()) {
-                        return innerQueryBuilder.get();
-                    }
-                    return null;
                 }
             } catch (IOException ex) {
                 throw new AliasFilterParsingException(index, alias.getAlias(), "Invalid alias filter", ex);

core/src/main/java/org/elasticsearch/search/rescore/QueryRescorerBuilder.java

@@ -26,7 +26,6 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.xcontent.ObjectParser;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
-import org.elasticsearch.index.query.QueryBuilders;
 import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.search.rescore.QueryRescorer.QueryRescoreContext;
@@ -57,7 +56,7 @@ public class QueryRescorerBuilder extends RescoreBuilder<QueryRescorerBuilder> {
     static {
         QUERY_RESCORE_PARSER.declareObject(InnerBuilder::setQueryBuilder, (p, c) -> {
             try {
-                return c.parseInnerQueryBuilder().orElse(QueryBuilders.matchAllQuery());
+                return c.parseInnerQueryBuilder();
             } catch (IOException e) {
                 throw new ParsingException(p.getTokenLocation(), "Could not parse inner query", e);
             }

core/src/main/java/org/elasticsearch/search/sort/GeoDistanceSortBuilder.java

@@ -62,7 +62,6 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * A geo distance based sorting on a geo point like field.
@@ -408,7 +407,7 @@ public class GeoDistanceSortBuilder extends SortBuilder<GeoDistanceSortBuilder>
         GeoDistance geoDistance = GeoDistance.DEFAULT;
         SortOrder order = SortOrder.ASC;
         SortMode sortMode = null;
-        Optional<QueryBuilder> nestedFilter = Optional.empty();
+        QueryBuilder nestedFilter = null;
         String nestedPath = null;
 
         boolean coerce = GeoValidationMethod.DEFAULT_LENIENT_PARSING;
@@ -493,7 +492,9 @@ public class GeoDistanceSortBuilder extends SortBuilder<GeoDistanceSortBuilder>
         if (sortMode != null) {
             result.sortMode(sortMode);
         }
-        nestedFilter.ifPresent(result::setNestedFilter);
+        if (nestedFilter != null) {
+            result.setNestedFilter(nestedFilter);
+        }
         result.setNestedPath(nestedPath);
         if (validation == null) {
             // looks like either validation was left unset or we are parsing old validation json

core/src/main/java/org/elasticsearch/search/sort/SortBuilder.java

@@ -203,9 +203,7 @@ public abstract class SortBuilder<T extends SortBuilder<T>> extends ToXContentTo
 
     protected static QueryBuilder parseNestedFilter(XContentParser parser, QueryParseContext context) {
         try {
-            QueryBuilder builder = context.parseInnerQueryBuilder().orElseThrow(() -> new ParsingException(parser.getTokenLocation(),
+            return context.parseInnerQueryBuilder();
-                    "Expected " + NESTED_FILTER_FIELD.getPreferredName() + " element."));
-            return builder;
         } catch (Exception e) {
             throw new ParsingException(parser.getTokenLocation(), "Expected " + NESTED_FILTER_FIELD.getPreferredName() + " element.", e);
         }

core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggester.java

@@ -34,14 +34,11 @@ import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.text.Text;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
-import org.elasticsearch.index.query.MatchNoneQueryBuilder;
 import org.elasticsearch.index.query.ParsedQuery;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.index.query.QueryShardContext;
-import org.elasticsearch.script.CompiledScript;
 import org.elasticsearch.script.ExecutableScript;
-import org.elasticsearch.script.ScriptService;
 import org.elasticsearch.search.suggest.Suggest.Suggestion;
 import org.elasticsearch.search.suggest.Suggest.Suggestion.Entry;
 import org.elasticsearch.search.suggest.Suggest.Suggestion.Entry.Option;
@@ -54,7 +51,6 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.function.Function;
 
 public final class PhraseSuggester extends Suggester<PhraseSuggestionContext> {
@@ -125,8 +121,8 @@ public final class PhraseSuggester extends Suggester<PhraseSuggestionContext> {
                     final ExecutableScript executable = collateScript.apply(vars);
                     final BytesReference querySource = (BytesReference) executable.run();
                     try (XContentParser parser = XContentFactory.xContent(querySource).createParser(querySource)) {
-                        Optional<QueryBuilder> innerQueryBuilder = shardContext.newParseContext(parser).parseInnerQueryBuilder();
+                        QueryBuilder innerQueryBuilder = shardContext.newParseContext(parser).parseInnerQueryBuilder();
-                        final ParsedQuery parsedQuery = shardContext.toQuery(innerQueryBuilder.orElse(new MatchNoneQueryBuilder()));
+                        final ParsedQuery parsedQuery = shardContext.toQuery(innerQueryBuilder);
                         collateMatch = Lucene.exists(searcher, parsedQuery.query());
                     }
                 }

core/src/test/java/org/elasticsearch/aliases/IndexAliasesIT.java

@@ -145,7 +145,9 @@ public class IndexAliasesIT extends ESIntegTestCase {
         ensureGreen();
 
         logger.info("--> aliasing index [test] with [alias1] and empty filter");
-        assertAcked(admin().indices().prepareAliases().addAlias("test", "alias1", "{}"));
+        IllegalArgumentException iae = expectThrows(IllegalArgumentException.class,
+                () -> admin().indices().prepareAliases().addAlias("test", "alias1", "{}").get());
+        assertEquals("failed to parse filter for alias [alias1]", iae.getMessage());
     }
 
     public void testSearchingFilteringAliasesSingleIndex() throws Exception {

core/src/test/java/org/elasticsearch/index/query/BoolQueryBuilderTests.java

@@ -46,7 +46,6 @@ import static org.elasticsearch.index.query.QueryBuilders.constantScoreQuery;
 import static org.elasticsearch.index.query.QueryBuilders.termQuery;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.instanceOf;
-import static org.hamcrest.CoreMatchers.startsWith;
 
 public class BoolQueryBuilderTests extends AbstractQueryTestCase<BoolQueryBuilder> {
     @Override
@@ -330,34 +329,6 @@ public class BoolQueryBuilderTests extends AbstractQueryTestCase<BoolQueryBuilde
         assertEquals(query, "kimchy", ((TermQueryBuilder)queryBuilder.must().get(0)).value());
     }
 
-    /**
-     * we ignore empty query bodies if we are not in strict mode
-     */
-    public void testFromJsonEmptyQueryBody() throws IOException {
-        String query =
-                "{" +
-                "\"bool\" : {" +
-                "  \"must\" : [ { } ]," +
-                "  \"filter\" : { }," +
-                "  \"must_not\" : [ { \"constant_score\" : {\"filter\" : { } } } ]" +
-                "}" +
-              "}";
-
-        BoolQueryBuilder queryBuilder = (BoolQueryBuilder) parseQuery(query, ParseFieldMatcher.EMPTY);
-        assertEquals(query, 0, queryBuilder.must().size());
-        assertEquals(query, 0, queryBuilder.filter().size());
-        assertEquals(query, 0, queryBuilder.mustNot().size());
-        assertEquals(query, 0, queryBuilder.should().size());
-        // we should have deprecation warning headers regardless of throwing an exception
-        checkWarningHeaders("query malformed, empty clause found at [1:27]",
-                "query malformed, empty clause found at [1:46]",
-                "query malformed, empty clause found at [1:100]");
-
-        IllegalArgumentException ex = expectThrows(IllegalArgumentException.class, () -> parseQuery(query, ParseFieldMatcher.STRICT));
-        assertThat(ex.getMessage(), startsWith("query malformed, empty clause found at"));
-        checkWarningHeaders("query malformed, empty clause found at [1:27]");
-    }
-
     /**
      * test that unknown query names in the clauses throw an error
      */

core/src/test/java/org/elasticsearch/index/query/BoostingQueryBuilderTests.java

@@ -21,18 +21,13 @@ package org.elasticsearch.index.query;
 
 import org.apache.lucene.queries.BoostingQuery;
 import org.apache.lucene.search.Query;
-import org.elasticsearch.common.ParseFieldMatcher;
-import org.elasticsearch.common.xcontent.XContentFactory;
-import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.search.internal.SearchContext;
 import org.elasticsearch.test.AbstractQueryTestCase;
 
 import java.io.IOException;
-import java.util.Optional;
 
-import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.instanceOf;
-import static org.hamcrest.CoreMatchers.nullValue;;
+import static org.hamcrest.CoreMatchers.nullValue;
 
 public class BoostingQueryBuilderTests extends AbstractQueryTestCase<BoostingQueryBuilder> {
 
@@ -94,45 +89,6 @@ public class BoostingQueryBuilderTests extends AbstractQueryTestCase<BoostingQue
         assertEquals(query, 5, queryBuilder.positiveQuery().boost(), 0.00001);
     }
 
-    /**
-     * we bubble up empty inner clauses as an empty optional
-     */
-    public void testFromJsonEmptyQueryBody() throws IOException {
-        String query =
-                "{ \"boosting\" : {" +
-                "    \"positive\" : { }, " +
-                "    \"negative\" : { \"match_all\" : {} }, " +
-                "    \"negative_boost\" : 23.0" +
-                "  }" +
-                "}";
-        XContentParser parser = XContentFactory.xContent(query).createParser(query);
-        QueryParseContext context = createParseContext(parser, ParseFieldMatcher.EMPTY);
-        Optional<QueryBuilder> innerQueryBuilder = context.parseInnerQueryBuilder();
-        assertTrue(innerQueryBuilder.isPresent() == false);
-
-        checkWarningHeaders("query malformed, empty clause found at [1:36]");
-
-        query =
-                "{ \"boosting\" : {\n" +
-                "    \"positive\" : { \"match_all\" : {} },\n" +
-                "    \"negative\" : { },\n" +
-                "    \"negative_boost\" : 23.0\n" +
-                "  }\n" +
-                "}";
-        parser = XContentFactory.xContent(query).createParser(query);
-        context = createParseContext(parser, ParseFieldMatcher.EMPTY);
-        innerQueryBuilder = context.parseInnerQueryBuilder();
-        assertTrue(innerQueryBuilder.isPresent() == false);
-
-        checkWarningHeaders("query malformed, empty clause found at [3:20]");
-
-        parser = XContentFactory.xContent(query).createParser(query);
-        QueryParseContext otherContext = createParseContext(parser, ParseFieldMatcher.STRICT);
-        IllegalArgumentException ex = expectThrows(IllegalArgumentException.class, () -> otherContext.parseInnerQueryBuilder());
-        assertThat(ex.getMessage(), equalTo("query malformed, empty clause found at [3:20]"));
-        checkWarningHeaders("query malformed, empty clause found at [3:20]");
-    }
-
     public void testRewrite() throws IOException {
         QueryBuilder positive = randomBoolean() ? new MatchAllQueryBuilder() : new WrapperQueryBuilder(new TermQueryBuilder("pos", "bar").toString());
         QueryBuilder negative = randomBoolean() ? new MatchAllQueryBuilder() : new WrapperQueryBuilder(new TermQueryBuilder("neg", "bar").toString());

core/src/test/java/org/elasticsearch/index/query/ConstantScoreQueryBuilderTests.java

@@ -21,17 +21,12 @@ package org.elasticsearch.index.query;
 
 import org.apache.lucene.search.ConstantScoreQuery;
 import org.apache.lucene.search.Query;
-import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.common.ParsingException;
-import org.elasticsearch.common.xcontent.XContentFactory;
-import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.search.internal.SearchContext;
 import org.elasticsearch.test.AbstractQueryTestCase;
 
 import java.io.IOException;
-import java.util.Optional;
 
-import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.instanceOf;
 import static org.hamcrest.CoreMatchers.nullValue;
 import static org.hamcrest.Matchers.containsString;
@@ -119,27 +114,4 @@ public class ConstantScoreQueryBuilderTests extends AbstractQueryTestCase<Consta
         assertEquals(json, 23.0, parsed.boost(), 0.0001);
         assertEquals(json, 42.0, parsed.innerQuery().boost(), 0.0001);
     }
-
-    /**
-     * we bubble up empty query bodies as an empty optional
-     */
-    public void testFromJsonEmptyQueryBody() throws IOException {
-        String query =
-                "{ \"constant_score\" : {" +
-                "    \"filter\" : { }" +
-                "  }" +
-                "}";
-        XContentParser parser = XContentFactory.xContent(query).createParser(query);
-        QueryParseContext context = createParseContext(parser, ParseFieldMatcher.EMPTY);
-        Optional<QueryBuilder> innerQueryBuilder = context.parseInnerQueryBuilder();
-        assertTrue(innerQueryBuilder.isPresent() == false);
-        checkWarningHeaders("query malformed, empty clause found at [1:40]");
-
-        parser = XContentFactory.xContent(query).createParser(query);
-        QueryParseContext otherContext = createParseContext(parser, ParseFieldMatcher.STRICT);
-        IllegalArgumentException ex = expectThrows(IllegalArgumentException.class, () -> otherContext.parseInnerQueryBuilder());
-        assertThat(ex.getMessage(), equalTo("query malformed, empty clause found at [1:40]"));
-        checkWarningHeaders("query malformed, empty clause found at [1:40]");
-    }
-
 }

core/src/test/java/org/elasticsearch/index/query/DisMaxQueryBuilderTests.java

@@ -22,10 +22,8 @@ package org.elasticsearch.index.query;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.search.BoostQuery;
 import org.apache.lucene.search.DisjunctionMaxQuery;
-import org.apache.lucene.search.MatchNoDocsQuery;
 import org.apache.lucene.search.PrefixQuery;
 import org.apache.lucene.search.Query;
-import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.search.internal.SearchContext;
 import org.elasticsearch.test.AbstractQueryTestCase;
 
@@ -85,23 +83,6 @@ public class DisMaxQueryBuilderTests extends AbstractQueryTestCase<DisMaxQueryBu
         return alternateVersions;
     }
 
-    /**
-     * Test with empty inner query body, this should be converted to a {@link MatchNoDocsQuery}.
-     * To test this, we use inner {@link ConstantScoreQueryBuilder} with empty inner filter.
-     */
-    public void testInnerQueryEmptyException() throws IOException {
-        String queryString = "{ \"" + DisMaxQueryBuilder.NAME + "\" :"
-                + "             { \"queries\" : [ {\"" + ConstantScoreQueryBuilder.NAME + "\" : { \"filter\" : { } } } ] "
-                + "             }"
-                + "           }";
-        QueryBuilder queryBuilder = parseQuery(queryString, ParseFieldMatcher.EMPTY);
-        QueryShardContext context = createShardContext();
-        Query luceneQuery = queryBuilder.toQuery(context);
-        assertThat(luceneQuery, instanceOf(MatchNoDocsQuery.class));
-        assertThat(luceneQuery.toString(), equalTo("MatchNoDocsQuery(\"no clauses for dismax query.\")"));
-        checkWarningHeaders("query malformed, empty clause found at [1:78]");
-    }
-
     public void testIllegalArguments() {
         DisMaxQueryBuilder disMaxQuery = new DisMaxQueryBuilder();
         expectThrows(IllegalArgumentException.class, () -> disMaxQuery.add(null));

core/src/test/java/org/elasticsearch/index/query/HasChildQueryBuilderTests.java

@@ -20,7 +20,6 @@
 package org.elasticsearch.index.query;
 
 import com.carrotsearch.randomizedtesting.generators.RandomPicks;
-
 import org.apache.lucene.queries.TermsQuery;
 import org.apache.lucene.search.BooleanClause;
 import org.apache.lucene.search.BooleanQuery;
@@ -33,11 +32,8 @@ import org.apache.lucene.search.similarities.PerFieldSimilarityWrapper;
 import org.apache.lucene.search.similarities.Similarity;
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
-import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.common.compress.CompressedXContent;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.common.xcontent.XContentFactory;
-import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.mapper.TypeFieldMapper;
 import org.elasticsearch.index.mapper.Uid;
@@ -53,7 +49,6 @@ import java.io.IOException;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Optional;
 
 import static org.hamcrest.CoreMatchers.containsString;
 import static org.hamcrest.CoreMatchers.equalTo;
@@ -223,28 +218,6 @@ public class HasChildQueryBuilderTests extends AbstractQueryTestCase<HasChildQue
         assertEquals(query, queryBuilder.innerHit(), expected);
     }
 
-    /**
-     * we resolve empty inner clauses by representing this whole query as empty optional upstream
-     */
-    public void testFromJsonEmptyQueryBody() throws IOException {
-        String query =  "{\n" +
-                "  \"has_child\" : {\n" +
-                "    \"query\" : { },\n" +
-                "    \"type\" : \"child\"" +
-                "   }" +
-                "}";
-        XContentParser parser = XContentFactory.xContent(query).createParser(query);
-        QueryParseContext context = createParseContext(parser, ParseFieldMatcher.EMPTY);
-        Optional<QueryBuilder> innerQueryBuilder = context.parseInnerQueryBuilder();
-        assertTrue(innerQueryBuilder.isPresent() == false);
-
-        parser = XContentFactory.xContent(query).createParser(query);
-        QueryParseContext otherContext = createParseContext(parser, ParseFieldMatcher.STRICT);
-        IllegalArgumentException ex = expectThrows(IllegalArgumentException.class, () -> otherContext.parseInnerQueryBuilder());
-        assertThat(ex.getMessage(), equalTo("query malformed, empty clause found at [3:17]"));
-        checkWarningHeaders("query malformed, empty clause found at [3:17]");
-    }
-
     public void testToQueryInnerQueryType() throws IOException {
         String[] searchTypes = new String[]{PARENT_TYPE};
         QueryShardContext shardContext = createShardContext();

core/src/test/java/org/elasticsearch/index/query/HasParentQueryBuilderTests.java

@@ -28,7 +28,6 @@ import org.elasticsearch.common.compress.CompressedXContent;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
-import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.search.fetch.subphase.InnerHitsContext;
 import org.elasticsearch.search.internal.SearchContext;
@@ -39,7 +38,6 @@ import org.elasticsearch.test.AbstractQueryTestCase;
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Optional;
 
 import static org.hamcrest.CoreMatchers.containsString;
 import static org.hamcrest.CoreMatchers.equalTo;
@@ -206,30 +204,6 @@ public class HasParentQueryBuilderTests extends AbstractQueryTestCase<HasParentQ
         assertEquals(json, "something", ((TermQueryBuilder) parsed.query()).value());
     }
 
-    /**
-     * we resolve empty inner clauses by representing this whole query as empty optional upstream
-     */
-    public void testFromJsonEmptyQueryBody() throws IOException {
-        String query =  "{\n" +
-                "  \"has_parent\" : {\n" +
-                "    \"query\" : { },\n" +
-                "    \"parent_type\" : \"blog\"" +
-                "   }" +
-                "}";
-        XContentParser parser = XContentFactory.xContent(query).createParser(query);
-        QueryParseContext context = createParseContext(parser, ParseFieldMatcher.EMPTY);
-        Optional<QueryBuilder> innerQueryBuilder = context.parseInnerQueryBuilder();
-        assertTrue(innerQueryBuilder.isPresent() == false);
-
-        checkWarningHeaders("query malformed, empty clause found at [3:17]");
-
-        parser = XContentFactory.xContent(query).createParser(query);
-        QueryParseContext otherContext = createParseContext(parser, ParseFieldMatcher.STRICT);
-        IllegalArgumentException ex = expectThrows(IllegalArgumentException.class, () -> otherContext.parseInnerQueryBuilder());
-        assertThat(ex.getMessage(), equalTo("query malformed, empty clause found at [3:17]"));
-        checkWarningHeaders("query malformed, empty clause found at [3:17]");
-    }
-
     public void testIgnoreUnmapped() throws IOException {
         final HasParentQueryBuilder queryBuilder = new HasParentQueryBuilder("unmapped", new MatchAllQueryBuilder(), false);
         queryBuilder.ignoreUnmapped(true);

core/src/test/java/org/elasticsearch/index/query/QueryParseContextTests.java

@@ -35,13 +35,8 @@ import org.junit.Before;
 import org.junit.BeforeClass;
 
 import java.io.IOException;
-import java.util.List;
-import java.util.Optional;
 
 import static java.util.Collections.emptyList;
-import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.Matchers.hasItem;
-import static org.hamcrest.Matchers.hasSize;
 
 public class QueryParseContextTests extends ESTestCase {
 
@@ -99,20 +94,8 @@ public class QueryParseContextTests extends ESTestCase {
         String source = query.toString();
         try (XContentParser parser = XContentFactory.xContent(source).createParser(source)) {
             QueryParseContext context = new QueryParseContext(indicesQueriesRegistry, parser, ParseFieldMatcher.STRICT);
-            Optional<QueryBuilder> actual = context.parseInnerQueryBuilder();
+            QueryBuilder actual = context.parseInnerQueryBuilder();
-            assertEquals(query, actual.get());
+            assertEquals(query, actual);
-        }
-    }
-
-    public void testParseInnerQueryBuilderEmptyBody() throws IOException {
-        String source = "{}";
-        try (XContentParser parser = XContentFactory.xContent(source).createParser(source)) {
-            QueryParseContext context = new QueryParseContext(indicesQueriesRegistry, parser, ParseFieldMatcher.EMPTY);
-            Optional<QueryBuilder> emptyQuery = context.parseInnerQueryBuilder();
-            assertFalse(emptyQuery.isPresent());
-            final List<String> warnings = threadContext.getResponseHeaders().get(DeprecationLogger.DEPRECATION_HEADER);
-            assertThat(warnings, hasSize(1));
-            assertThat(warnings, hasItem(equalTo("query malformed, empty clause found at [1:2]")));
         }
     }
 
@@ -128,12 +111,9 @@ public class QueryParseContextTests extends ESTestCase {
 
         source = "{}";
         try (XContentParser parser = JsonXContent.jsonXContent.createParser(source)) {
-            QueryParseContext context = new QueryParseContext(indicesQueriesRegistry, parser, ParseFieldMatcher.STRICT);
+            QueryParseContext context = new QueryParseContext(indicesQueriesRegistry, parser, ParseFieldMatcher.EMPTY);
             IllegalArgumentException exception = expectThrows(IllegalArgumentException.class, () ->  context.parseInnerQueryBuilder());
             assertEquals("query malformed, empty clause found at [1:2]", exception.getMessage());
-            final List<String> warnings = threadContext.getResponseHeaders().get(DeprecationLogger.DEPRECATION_HEADER);
-            assertThat(warnings, hasSize(1));
-            assertThat(warnings, hasItem(equalTo("query malformed, empty clause found at [1:2]")));
         }
 
         source = "{ \"foo\" : \"bar\" }";
@@ -149,9 +129,5 @@ public class QueryParseContextTests extends ESTestCase {
             ParsingException exception = expectThrows(ParsingException.class, () ->  context.parseInnerQueryBuilder());
             assertEquals("no [query] registered for [foo]", exception.getMessage());
         }
-        final List<String> warnings = threadContext.getResponseHeaders().get(DeprecationLogger.DEPRECATION_HEADER);
-        assertThat(warnings, hasSize(1));
-        assertThat(warnings, hasItem(equalTo("query malformed, empty clause found at [1:2]")));
     }
-
 }

core/src/test/java/org/elasticsearch/index/query/plugin/DummyQueryBuilder.java

@@ -30,7 +30,6 @@ import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.index.query.plugin.DummyQueryParserPlugin.DummyQuery;
 
 import java.io.IOException;
-import java.util.Optional;
 
 public class DummyQueryBuilder extends AbstractQueryBuilder<DummyQueryBuilder> {
     public static final String NAME = "dummy";
@@ -52,10 +51,10 @@ public class DummyQueryBuilder extends AbstractQueryBuilder<DummyQueryBuilder> {
         builder.startObject(NAME).endObject();
     }
 
-    public static Optional<DummyQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static DummyQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser.Token token = parseContext.parser().nextToken();
         assert token == XContentParser.Token.END_OBJECT;
-        return Optional.of(new DummyQueryBuilder());
+        return new DummyQueryBuilder();
     }
 
     @Override

core/src/test/java/org/elasticsearch/search/aggregations/bucket/FilterIT.java

@@ -21,17 +21,10 @@ package org.elasticsearch.search.aggregations.bucket;
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.action.index.IndexRequestBuilder;
 import org.elasticsearch.action.search.SearchResponse;
-import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.common.xcontent.XContentBuilder;
-import org.elasticsearch.common.xcontent.XContentFactory;
-import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.query.BoolQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
-import org.elasticsearch.index.query.QueryParseContext;
-import org.elasticsearch.indices.query.IndicesQueriesRegistry;
-import org.elasticsearch.search.aggregations.AggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.filter.Filter;
-import org.elasticsearch.search.aggregations.bucket.filter.FilterAggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.histogram.Histogram;
 import org.elasticsearch.search.aggregations.metrics.avg.Avg;
 import org.elasticsearch.test.ESIntegTestCase;
@@ -122,24 +115,6 @@ public class FilterIT extends ESIntegTestCase {
         assertThat(filter.getDocCount(), equalTo((long) numDocs));
     }
 
-    /**
-     * test that "{ "filter" : {} }" is regarded as match_all when not parsing strict
-     */
-    public void testEmptyFilter() throws Exception {
-        String emtpyFilterBody = "{ }";
-        XContentParser parser = XContentFactory.xContent(emtpyFilterBody).createParser(emtpyFilterBody);
-        QueryParseContext parseContext = new QueryParseContext(new IndicesQueriesRegistry(), parser, ParseFieldMatcher.EMPTY);
-        AggregationBuilder filterAgg = FilterAggregationBuilder.parse("tag1", parseContext);
-
-        SearchResponse response = client().prepareSearch("idx").addAggregation(filterAgg).execute().actionGet();
-
-        assertSearchResponse(response);
-
-        Filter filter = response.getAggregations().get("tag1");
-        assertThat(filter, notNullValue());
-        assertThat(filter.getDocCount(), equalTo((long) numDocs));
-    }
-
     public void testWithSubAggregation() throws Exception {
         SearchResponse response = client().prepareSearch("idx")
                 .addAggregation(filter("tag1", termQuery("tag", "tag1"))

core/src/test/java/org/elasticsearch/search/aggregations/bucket/FiltersIT.java

@@ -22,17 +22,10 @@ package org.elasticsearch.search.aggregations.bucket;
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.action.index.IndexRequestBuilder;
 import org.elasticsearch.action.search.SearchResponse;
-import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.common.xcontent.XContentBuilder;
-import org.elasticsearch.common.xcontent.XContentFactory;
-import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.query.BoolQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
-import org.elasticsearch.index.query.QueryParseContext;
-import org.elasticsearch.indices.query.IndicesQueriesRegistry;
-import org.elasticsearch.search.aggregations.AggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.filters.Filters;
-import org.elasticsearch.search.aggregations.bucket.filters.FiltersAggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.filters.FiltersAggregator.KeyedFilter;
 import org.elasticsearch.search.aggregations.bucket.histogram.Histogram;
 import org.elasticsearch.search.aggregations.metrics.avg.Avg;
@@ -205,45 +198,9 @@ public class FiltersIT extends ESIntegTestCase {
         assertThat(avgValue, notNullValue());
         assertThat(avgValue.getName(), equalTo("avg_value"));
         assertThat(avgValue.getValue(), equalTo((double) sum / numTag2Docs));
-        assertThat((String) propertiesKeys[1], equalTo("tag2"));
+        assertThat(propertiesKeys[1], equalTo("tag2"));
-        assertThat((long) propertiesDocCounts[1], equalTo((long) numTag2Docs));
+        assertThat(propertiesDocCounts[1], equalTo((long) numTag2Docs));
-        assertThat((double) propertiesCounts[1], equalTo((double) sum / numTag2Docs));
+        assertThat(propertiesCounts[1], equalTo((double) sum / numTag2Docs));
-    }
-
-    public void testEmptyFilter() throws Exception {
-        String emtpyFilterBody = "{ \"filters\" : [ {} ] }";
-        XContentParser parser = XContentFactory.xContent(emtpyFilterBody).createParser(emtpyFilterBody);
-        parser.nextToken();
-        QueryParseContext parseContext = new QueryParseContext(new IndicesQueriesRegistry(), parser, ParseFieldMatcher.EMPTY);
-        AggregationBuilder filtersAgg = FiltersAggregationBuilder.parse("tag1", parseContext);
-
-        SearchResponse response = client().prepareSearch("idx").addAggregation(filtersAgg).execute().actionGet();
-
-        assertSearchResponse(response);
-
-        Filters filter = response.getAggregations().get("tag1");
-        assertThat(filter, notNullValue());
-        assertThat(filter.getBuckets().size(), equalTo(1));
-        assertThat(filter.getBuckets().get(0).getDocCount(), equalTo((long) numDocs));
-    }
-
-    public void testEmptyKeyedFilter() throws Exception {
-        String emtpyFilterBody = "{ \"filters\" : {\"foo\" : {} } }";
-        XContentParser parser = XContentFactory.xContent(emtpyFilterBody).createParser(emtpyFilterBody);
-        parser.nextToken();
-        QueryParseContext parseContext = new QueryParseContext(new IndicesQueriesRegistry(), parser, ParseFieldMatcher.EMPTY);
-        AggregationBuilder filtersAgg = FiltersAggregationBuilder.parse("tag1", parseContext);
-
-        SearchResponse response = client().prepareSearch("idx").addAggregation(filtersAgg)
-                .execute().actionGet();
-
-        assertSearchResponse(response);
-
-        Filters filter = response.getAggregations().get("tag1");
-        assertThat(filter, notNullValue());
-        assertThat(filter.getBuckets().size(), equalTo(1));
-        assertThat(filter.getBuckets().get(0).getKey(), equalTo("foo"));
-        assertThat(filter.getBuckets().get(0).getDocCount(), equalTo((long) numDocs));
     }
 
     public void testAsSubAggregation() {
@@ -444,9 +401,9 @@ public class FiltersIT extends ESIntegTestCase {
         assertThat(avgValue, notNullValue());
         assertThat(avgValue.getName(), equalTo("avg_value"));
         assertThat(avgValue.getValue(), equalTo((double) sum / numTag1Docs));
-        assertThat((String) propertiesKeys[0], equalTo("tag1"));
+        assertThat(propertiesKeys[0], equalTo("tag1"));
-        assertThat((long) propertiesDocCounts[0], equalTo((long) numTag1Docs));
+        assertThat(propertiesDocCounts[0], equalTo((long) numTag1Docs));
-        assertThat((double) propertiesCounts[0], equalTo((double) sum / numTag1Docs));
+        assertThat(propertiesCounts[0], equalTo((double) sum / numTag1Docs));
 
         bucket = filters.getBucketByKey("tag2");
         assertThat(bucket, Matchers.notNullValue());
@@ -460,9 +417,9 @@ public class FiltersIT extends ESIntegTestCase {
         assertThat(avgValue, notNullValue());
         assertThat(avgValue.getName(), equalTo("avg_value"));
         assertThat(avgValue.getValue(), equalTo((double) sum / numTag2Docs));
-        assertThat((String) propertiesKeys[1], equalTo("tag2"));
+        assertThat(propertiesKeys[1], equalTo("tag2"));
-        assertThat((long) propertiesDocCounts[1], equalTo((long) numTag2Docs));
+        assertThat(propertiesDocCounts[1], equalTo((long) numTag2Docs));
-        assertThat((double) propertiesCounts[1], equalTo((double) sum / numTag2Docs));
+        assertThat(propertiesCounts[1], equalTo((double) sum / numTag2Docs));
 
         bucket = filters.getBucketByKey("_other_");
         assertThat(bucket, Matchers.notNullValue());
@@ -476,9 +433,9 @@ public class FiltersIT extends ESIntegTestCase {
         assertThat(avgValue, notNullValue());
         assertThat(avgValue.getName(), equalTo("avg_value"));
         assertThat(avgValue.getValue(), equalTo((double) sum / numOtherDocs));
-        assertThat((String) propertiesKeys[2], equalTo("_other_"));
+        assertThat(propertiesKeys[2], equalTo("_other_"));
-        assertThat((long) propertiesDocCounts[2], equalTo((long) numOtherDocs));
+        assertThat(propertiesDocCounts[2], equalTo((long) numOtherDocs));
-        assertThat((double) propertiesCounts[2], equalTo((double) sum / numOtherDocs));
+        assertThat(propertiesCounts[2], equalTo((double) sum / numOtherDocs));
     }
 
     public void testEmptyAggregationWithOtherBucket() throws Exception {

core/src/test/java/org/elasticsearch/search/builder/SearchSourceBuilderTests.java

@@ -22,7 +22,6 @@ package org.elasticsearch.search.builder;
 import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.common.ParsingException;
-import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.io.stream.NamedWriteableAwareStreamInput;
@@ -315,16 +314,4 @@ public class SearchSourceBuilderTests extends AbstractSearchTestCase {
             assertEquals("query", sourceAsMap.keySet().iterator().next());
         }
     }
-
-    public void testEmptyPostFilter() throws IOException {
-        SearchSourceBuilder builder = new SearchSourceBuilder();
-        String query = "{ \"post_filter\": {} }";
-        assertParseSearchSource(builder, new BytesArray(query), ParseFieldMatcher.EMPTY);
-    }
-
-    public void testEmptyQuery() throws IOException {
-        SearchSourceBuilder builder = new SearchSourceBuilder();
-        String query = "{ \"query\": {} }";
-        assertParseSearchSource(builder, new BytesArray(query), ParseFieldMatcher.EMPTY);
-    }
 }

docs/reference/migration/migrate_6_0/search.asciidoc

@@ -23,6 +23,9 @@
 
 * The deprecated `indices` query has been removed.
 
+* Support for empty query objects (`{ }`) has been removed from the query DSL.
+  An error is thrown whenever an empty query object is provided.
+
 ==== Search shards API
 
 The search shards API no longer accepts the `type` url parameter, which didn't

modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TemplateQueryBuilder.java

@@ -19,7 +19,6 @@
 package org.elasticsearch.script.mustache;
 
 import org.apache.lucene.search.Query;
-import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
@@ -42,7 +41,6 @@ import java.io.IOException;
 import java.util.Collections;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 
 /**
  * Facilitates creating template query requests.
@@ -122,8 +120,7 @@ public class TemplateQueryBuilder extends AbstractQueryBuilder<TemplateQueryBuil
         BytesReference querySource = queryRewriteContext.getTemplateBytes(template);
         try (XContentParser qSourceParser = XContentFactory.xContent(querySource).createParser(querySource)) {
             final QueryParseContext queryParseContext = queryRewriteContext.newParseContext(qSourceParser);
-            final QueryBuilder queryBuilder = queryParseContext.parseInnerQueryBuilder().orElseThrow(
+            final QueryBuilder queryBuilder = queryParseContext.parseInnerQueryBuilder();
-                    () -> new ParsingException(qSourceParser.getTokenLocation(), "inner query in [" + NAME + "] cannot be empty"));
             if (boost() != DEFAULT_BOOST || queryName() != null) {
                 final BoolQueryBuilder boolQueryBuilder = new BoolQueryBuilder();
                 boolQueryBuilder.must(queryBuilder);
@@ -137,9 +134,9 @@ public class TemplateQueryBuilder extends AbstractQueryBuilder<TemplateQueryBuil
      * In the simplest case, parse template string and variables from the request,
      * compile the template and execute the template against the given variables.
      */
-    public static Optional<TemplateQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static TemplateQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         Script template = Script.parse(parser, parseContext.getParseFieldMatcher(), "mustache");
-        return Optional.of(new TemplateQueryBuilder(template));
+        return new TemplateQueryBuilder(template);
     }
 }

modules/percolator/src/main/java/org/elasticsearch/percolator/PercolateQueryBuilder.java

@@ -75,7 +75,6 @@ import org.elasticsearch.index.query.QueryShardException;
 
 import java.io.IOException;
 import java.util.Objects;
-import java.util.Optional;
 
 import static org.elasticsearch.index.mapper.SourceToParse.source;
 import static org.elasticsearch.percolator.PercolatorFieldMapper.parseQuery;
@@ -233,7 +232,7 @@ public class PercolateQueryBuilder extends AbstractQueryBuilder<PercolateQueryBu
         builder.endObject();
     }
 
-    public static Optional<PercolateQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException {
+    public static PercolateQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException {
         XContentParser parser = parseContext.parser();
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
 
@@ -314,7 +313,7 @@ public class PercolateQueryBuilder extends AbstractQueryBuilder<PercolateQueryBu
         }
         queryBuilder.queryName(queryName);
         queryBuilder.boost(boost);
-        return Optional.of(queryBuilder);
+        return queryBuilder;
     }
 
     @Override

modules/percolator/src/main/java/org/elasticsearch/percolator/PercolatorFieldMapper.java

@@ -345,8 +345,7 @@ public class PercolatorFieldMapper extends FieldMapper {
 
     private static QueryBuilder parseQueryBuilder(QueryParseContext context, XContentLocation location) {
         try {
-            return context.parseInnerQueryBuilder()
+            return context.parseInnerQueryBuilder();
-                    .orElseThrow(() -> new ParsingException(location, "Failed to parse inner query, was empty"));
         } catch (IOException e) {
             throw new ParsingException(location, "Failed to parse", e);
         }

modules/percolator/src/main/java/org/elasticsearch/percolator/TransportPercolateAction.java

@@ -209,7 +209,7 @@ public class TransportPercolateAction extends HandledTransportAction<PercolateRe
             try (XContentParser parser = XContentHelper.createParser(querySource)) {
                 QueryParseContext queryParseContext = new QueryParseContext(queryRegistry, parser, parseFieldMatcher);
                 BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
-                queryParseContext.parseInnerQueryBuilder().ifPresent(boolQueryBuilder::must);
+                boolQueryBuilder.must(queryParseContext.parseInnerQueryBuilder());
                 boolQueryBuilder.filter(percolateQueryBuilder);
                 searchSource.field("query", boolQueryBuilder);
             }

modules/percolator/src/test/java/org/elasticsearch/percolator/PercolatorFieldMapperTests.java

@@ -480,10 +480,9 @@ public class PercolatorFieldMapperTests extends ESSingleNodeTestCase {
         QueryParseContext qsc = indexService.newQueryShardContext(
                 randomInt(20), null, () -> { throw new UnsupportedOperationException(); })
                 .newParseContext(sourceParser);
-        assertThat(qsc.parseInnerQueryBuilder().get(), equalTo(expected));
+        assertThat(qsc.parseInnerQueryBuilder(), equalTo(expected));
     }
 
-
     public void testEmptyName() throws Exception {
         // after 5.x
         String mapping = XContentFactory.jsonBuilder().startObject().startObject("type1")

qa/smoke-test-http/src/test/java/org/elasticsearch/http/TestDeprecatedQueryBuilder.java

@@ -33,7 +33,6 @@ import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.index.query.QueryShardContext;
 
 import java.io.IOException;
-import java.util.Optional;
 
 /**
  * A query that performs a <code>match_all</code> query, but with each <em>index</em> touched getting a unique deprecation warning.
@@ -66,14 +65,14 @@ public class TestDeprecatedQueryBuilder extends AbstractQueryBuilder<TestDepreca
         builder.startObject(NAME).endObject();
     }
 
-    public static Optional<TestDeprecatedQueryBuilder> fromXContent(QueryParseContext parseContext) throws IOException, ParsingException {
+    public static TestDeprecatedQueryBuilder fromXContent(QueryParseContext parseContext) throws IOException, ParsingException {
         XContentParser parser = parseContext.parser();
 
         if (parser.nextToken() != XContentParser.Token.END_OBJECT) {
             throw new ParsingException(parser.getTokenLocation(), "[{}] query does not have any fields", NAME);
         }
 
-        return Optional.of(new TestDeprecatedQueryBuilder());
+        return new TestDeprecatedQueryBuilder();
     }
 
     @Override

test/framework/src/main/java/org/elasticsearch/test/AbstractQueryTestCase.java

@@ -591,8 +591,7 @@ public abstract class AbstractQueryTestCase<QB extends AbstractQueryBuilder<QB>>
 
     private static QueryBuilder parseQuery(XContentParser parser, ParseFieldMatcher matcher) throws IOException {
         QueryParseContext context = createParseContext(parser, matcher);
-        QueryBuilder parseInnerQueryBuilder = context.parseInnerQueryBuilder()
+        QueryBuilder parseInnerQueryBuilder = context.parseInnerQueryBuilder();
-                .orElseThrow(() -> new IllegalArgumentException("inner query body cannot be empty"));
         assertNull(parser.nextToken());
         return parseInnerQueryBuilder;
     }